How Do Natural Resources Inﬂuence
Civil War? Evidence from
Thirteen Cases
Michael L+ Ross
Abstract Recent studies have found that natural resources and civil war are highly
correlated+ Yet the causal mechanisms behind the correlation are not well understood,
in part because data on civil wars is scarce and of poor quality+ In this article
I examine thirteen recent civil wars to explore the mechanisms behind the resourceconﬂict
correlation+ I describe seven hypotheses about how resources may inﬂuence
a conﬂict, specify the observable implications of each, and report which mechanisms
can be observed in a sample of thirteen civil wars in which natural resources were
“most likely” to have played a role+ I ﬁnd that two of the most widely cited causal
mechanisms do not appear to be valid; that oil, nonfuel minerals, and drugs are causally
linked to conﬂict, but legal agricultural commodities are not; and that resource
wealth and civil war are linked by a variety of mechanisms, including several that
others had not identiﬁed+
Recent studies have found that natural resources and civil war are highly corre-
lated+1
According to Collier and Hoefﬂer,2
states that rely heavily on the export of
primary commodities face a higher risk of civil war than resource-poor states+ Fearon
and Laitin, and de Soysa,3
each using unique data sets, ﬁnd that oil-exporting states
are more likely to suffer from civil wars+ Fearon also shows that the presence of
certain types of resources ~gemstones and narcotics! tends to make wars last lon-
ger;4
similarly, Doyle and Sambanis demonstrate that civil wars are harder to end
when they occur in countries that depend on primary commodity exports+5
Buhaug
and Gates show that the presence of mineral resources in a conﬂict zone tends to
increase a conﬂict’s geographical scope+6
For their comments on earlier drafts, I am grateful to Paul Collier, J+ R+ Deshazo, Pierre Englebert,
Barbara Geddes, Anke Hoefﬂer, Macartan Humphreys, Philippe Le Billon, Roy Licklider, Dan Posner,
Ken Shultz, and Libby Wood+
1+ For a review of recent ﬁndings on national resources and civil war, see Ross 2004+
2+ Collier and Hoefﬂer 1998 and 2002a+
3+ See Fearon and Laitin 2003; de Soysa 2002+
4+ Fearon 2004+
5+ Doyle and Sambanis 2000+
6+ Buhaug and Gates 2002+
International Organization 58, Winter 2004, pp+ 35–67
© 2004 by The IO Foundation+ DOI: 10+10170S002081830458102X
There is little agreement among these and other scholars on why natural resources
have these effects: most scholars have little to say about causal
mechanisms—the processes that link “resources” to “conﬂict+” Journalists often
claim that resources have “fueled” a given conﬂict, but are vague about how this
occurred+
Identifying the mechanisms that link resources to civil war would make these
theories more complete and persuasive: statistical correlations can only take one
so far+ Specifying the mechanism would also address three problems in the natural
resources–civil wars literature+ First, it could help resolve nagging concerns about
endogeneity and spuriousness+ The natural resource–civil war correlation, for example,
might be the opposite of what it appears: civil wars might produce resource
dependence by forcing a country’s manufacturing sector to ﬂee while leaving
its resource sector—which is location-speciﬁc and cannot depart—as the major
force in the economy by default+ Even though most scholars employ lagged independent
variables in their regressions, this method does not rule out reverse causality:
because civil wars do not ofﬁcially “begin” until they have crossed some
threshold of violence, they might be preceded by years of low-level hostilities that
drive off manufacturing ﬁrms, producing a higher level of resource dependence
before the civil war is coded as commencing+
The natural resource–civil war correlation could also be spurious: both civil
war and resource dependence might be independently caused by some unmeasured
third variable, such as a weak rule of law+ A state where the rule of law is
weak might be unable to attract investment in its manufacturing sector, and hence
would depend more heavily on resource exports; this state might also face a heightened
risk of civil war through a different process+ The result could be a statistically
signiﬁcant correlation between resource dependence and civil war, even though
neither factor would cause the other+
Second, identifying the causal mechanisms could help settle disagreements among
the statistical studies over which resources matter, and what dimensions of conﬂict
they tend to inﬂuence+ Collier and Hoefﬂer,7
for example, ﬁnd that primary
commodities of all types—including oil, minerals, and agricultural goods—are
linked to the onset of war+ Both Fearon and Laitin, and de Soysa dispute this claim8
and suggest that only oil matters+ Collier, Hoefﬂer, and Söderbom suggest that
primary commodities have no inﬂuence on the duration of conﬂict, a claim that is
apparently contradicted by Doyle and Sambanis, and Stedman+9
Fearon, meanwhile,
suggests that contraband commodities, such as diamonds and drugs, make
wars last longer+10
A closer look at case studies may help resolve some of these
contradictions+
7+ Collier and Hoefﬂer 2002a+
8+ See Fearon and Laitin 2003; de Soysa 2002+
9+ See Collier, Hoefﬂer, and Söderbom 2001; Doyle and Sambanis 2000; Stedman 2001+
10+ Fearon forthcoming+
36 International Organization
Finally, different mechanisms suggest different policy interventions+ For example,
if mining causes conﬂict because it produces grievances over environmental
degradation and access to jobs, the solution might be greater community involvement
on the part of mining ﬁrms+ But if conﬂicts occur because mining provides
extortion opportunities for rebel groups and warlords, the solution might be stricter
mine site security and less community involvement+ The United Nations ~UN!
Security Council, the World Bank, and the Group of 8 ~G8! industrial nations have
all been engaged in policy responses to the resource–civil war issue, making this
concern highly salient+
Identifying the correct causal mechanisms, however, is not a simple endeavor+
Some of the purported causal mechanisms have been carefully speciﬁed, but most
have not+ Once speciﬁed, it is not clear how these mechanisms can be tested+ If
one had sufﬁciently high-quality data for a large number of civil wars, one could
use a large-N study, placing intervening variables on the right-hand side of regressions
on war onset or war duration+ Unfortunately, data on the requisite dimensions
of conﬂict are scarce and typically of poor quality+
In this article I use a small-N approach to circumvent this problem+ I begin by
identifying seven causal mechanisms that might account for the resource–civil war
correlation, and I suggest how they might be conﬁrmed or disconﬁrmed in case
studies+11
I then select a sample of thirteen recent civil wars on a “most likely”
basis, as described in the second section+ In the third section I report which of the
causal mechanisms—or rather, which of their observable implications—are present
in the thirteen cases, as well as in subsets of “separatist” and “nonseparatist” civil
wars; I also illustrate some of the causal mechanisms at work+ In the fourth section
I describe four additional mechanisms that I observed in the sample, but which
had not been hypothesized ex ante+ The ﬁnal section concludes+
My approach is based on a “most likely” research design, in which a scholar
examines in depth a single case in which a hypothesized causal relationship is
believed “most likely” to be found; if it is present, the hypothesis is pronounced
“plausible,” and if not, it is deemed “falsiﬁed+”12
Similar to other small-N methods,
the most likely approach has valuable properties: it pays close attention to
the validity of concepts and to causal linkages; it helps account for variables that
are difﬁcult to measure; and it is sensitive to case-speciﬁc factors+ The heightened
attention to validity, however, has a cost: because the sample is biased, the ﬁndings
cannot be generalized to some larger set of unexamined cases+ Still, a systematic
study of most likely cases can probe and reﬁne the plausibility of existing
hypotheses and generate new ones for future, out-of-sample tests+
My analysis generates eight ﬁndings about the thirteen cases: ~1! certain types
of natural resources—oil, gemstones, and drugs—have indeed inﬂuenced the onset
11+ I also describe two further hypotheses that, unfortunately, cannot be conﬁrmed or disconﬁrmed
at the case study level+
12+ Eckstein 1975+
Natural Inﬂuences and Civil War 37
and duration of civil wars; ~2! other types of primary commodities—in particular,
legal agricultural commodities—did not have an effect on civil wars; ~3! there
was little or no evidence to support two of the most commonly cited causal mechanisms;
~4! illicit drugs did not lead to the onset of conﬂict, although they did
lengthen preexisting conﬂicts; ~5! resources played a different role in the sample’s
three separatist conﬂicts than they did in the ten nonseparatist conﬂicts; ~6! resources
did not necessarily make conﬂicts longer or more severe—at times they
appeared to shorten conﬂicts and promote cooperation among opposing sides; and
~7! most civil wars in the sample were inﬂuenced by natural resources through
several mechanisms simultaneously, which may help account for the analytical
muddle of some earlier studies+ ~8! Finally, several unanticipated mechanisms linked
resources and conﬂict in the thirteen cases: foreign intervention, futures contracts
for war booty, and preemptive repression in resource-rich areas+
Hypotheses About Resources and Conﬂict
Below I describe seven testable hypotheses about the mechanisms that link natural
resources and civil war+ For the sake of completeness, I also discuss two further
hypotheses that I am unable to test at the case study level+ The nine mechanisms
are listed in Figure 1+ The ﬁrst four hypotheses describe ways that resource wealth
could lead to the onset of conﬂict; the next three suggest ways that resource wealth
could inﬂuence the duration of a conﬂict; and the ﬁnal two describe how resource
wealth might inﬂuence the intensity of a conﬂict—that is, the casualty rate+13
I include the hypotheses on conﬂict intensity because it is possible that the resource
wealth–civil war correlation is produced solely ~or partly! by an intensity
effect+ To become classiﬁed as a civil war, a conﬂict must pass a certain threshold,
producing at least one thousand combat-related deaths over some period of time+
The presence of resource wealth might turn low-intensity conﬂicts into highintensity
conﬂicts without inﬂuencing the total number of conﬂicts; this could produce
a statistical correlation between resource dependence and the incidence of
civil war by increasing the number of conﬂicts that cross the critical threshold+
13+ I use the terms “resource wealth” and “resource dependence” interchangeably here+ Most of the
large-N studies measure the correlation between civil war and resource dependence, deﬁned as the
ratio of natural resource exports ~including oil, gas, minerals, and agricultural commodities! to gross
domestic product ~GDP!+ Most scholars treat this as an indicator of the relative abundance of natural
resource wealth in the economy+ But resource dependence is a less-than-ideal indicator: it is sensitive
to changes in the size of the nonresource sector, and the size of GDP; moreover, it fails to capture
natural resources that are produced and consumed domestically, or exported illegally+ Two of the cases
in my sample ~Afghanistan and Cambodia! were strongly inﬂuenced by illicit resources, even though
they have low levels of resource dependence ~see Table 1!+
To avoid these problems in the case studies, I examine whether the conﬂicts were inﬂuenced by any
type of domestically produced and commercially valuable natural resource, regardless of its legality or
export status+
38 International Organization
Similarly, if resource wealth increased the number of years in which the conﬂict
crossed the thousand-death threshold without inﬂuencing the conﬂict’s beginning
and end dates, it could produce a spurious correlation between resource wealth
and duration+ Hence it is useful to explore whether resource wealth has an inﬂuence
on the intensity of civil wars+
The nine hypotheses below were taken from other scholars’ accounts of resourcebased
civil wars+ Often these scholars discussed causal mechanisms brieﬂy or indirectly;
I have tried to turn their implicit hypotheses into explicit ones+ Some of
the mechanisms are linked to each other+ By treating them as discrete mechanisms,
I can specify them more clearly and test them more directly+ None of the
mechanisms are mutually exclusive, and most scholars cited below discuss multiple
causal mechanisms+
Onset of Civil War
The presence of resource wealth might cause the onset of civil wars in four ways,
three of which can be tested with case studies+ Perhaps the most inﬂuential hyFIGURE
1. Hypothesized causal mechanisms
Natural Inﬂuences and Civil War 39
pothesis on resources and conﬂict comes from the work of Collier and Hoefﬂer+14
I refer to this hypothesis as the “looting” mechanism+ Collier and Hoefﬂer suggest
that explanations for civil wars fall into two categories: those that focus on the
motives or “grievances” of rebel organizations, and those that focus on their funding+
The most signiﬁcant funding opportunities for insurgents, they suggest, tend
to come from exportable natural resources: if rebels can extract and sell resources,
or extort money from those who do, then they are more likely to launch a civil
war+ Their explanation parallels Keen’s argument that in the post–Cold War era,
rebel groups have replaced the funding they once received from their superpower
sponsors with money from looted natural resources+15
The Collier-Hoefﬂer argument comes from their observation that natural resources
offer rebel groups unusual funding opportunities, because resources typically
produce rents and are location-speciﬁc+ If rebels try to loot or extort money
from manufacturing ﬁrms, the ﬁrms will relocate to a safe area or be forced out of
business; but if rebels extort money from resource ﬁrms, the ﬁrms cannot relocate
and can often make payments to rebels and still turn a proﬁt+ States whose economies
are more heavily based on resource exports should, therefore, also face a
higher risk of civil wars+
Collier and Hoefﬂer do not suggest that rebels launch a conﬂict in anticipation
of resource wealth; rather, they argue that rebels use looted resource wealth in the
prewar phase to buy arms and hire soldiers—thus funding the “start-up costs” of
initiating a rebellion+ This subsequently allows them to challenge government forces
strongly enough to generate at least one thousand battle-related deaths, thus producing
a conﬂict large enough to be classiﬁed as a “civil war+”
In their empirical tests, Collier and Hoefﬂer ﬁnd that the effect of a country’s
primary commodity exports on its conﬂict risk is “both highly signiﬁcant and considerable”;
they state, “we have interpreted ~this correlation! as being due to the
opportunities such commodities provide for extortion, making rebellion feasible
and even attractive+”16
They reject the possibility that primary commodities lead
to conﬂict through a grievance mechanism+
The “looting” mechanism might be stated as the following:
H1: Primary commodities increase the probability of civil war by enabling nascent
rebel groups to raise money either by extracting and selling the commodities
directly, or by extorting money from others who do.
14+ Collier and Hoefﬂer 2002a+
15+ Keen 1998+
16+ Collier and Hoefﬂer 2002a, 16+ Collier and Hoefﬂer estimate that the correlation between resource
dependence and civil war is curvilinear, suggesting that the risk of civil war declines when
resource dependence reaches exceptionally high levels, at which point “the increased tax revenue eventually
augments the capacity of the government to defend itself sufﬁciently to offset the enhanced
ﬁnances of the rebels+” Other scholars, such as Hegre, estimate the correlation to be linear+ Hegre
2002+
40 International Organization
If this hypothesis is correct, then in case studies one should observe rebel organizations
raising money before the start of the civil war, through the extraction and
sale of natural resources, or from the extortion of resource ﬁrms+17
The second possible mechanism—which has been widely cited by policy analysts
and journalists—is a “grievance” mechanism+ It suggests that resource
extraction creates grievances among the local population, because of land expropriation,
environmental hazards, insufﬁcient job opportunities, and the social disruptions
caused by labor migration; these grievances, in turn, lead to civil war+
Klare, for example, suggests that “resource wars” are caused in part by logging or
mining ﬁrms that are “ravaging the environment” and “driving off the people who
have long inhabited the area or depriving them of any beneﬁts from the appropriation
of their traditional lands+”18
Gedicks and Switzer offer similar arguments;
so do many journalists+19
These arguments suggest the following:
H2: Resource wealth increases the probability of civil war by causing grievances
over insufﬁciently compensated land expropriation, environmental degradation, inadequate
job opportunities, and labor migration+
If resource exploitation leads to civil war through a grievance mechanism, one
should observe the rebels criticizing resource ﬁrms or the resource sector in their
propaganda; and one should see rebels make resource ﬁrms a target of their violence,
apart from looting or extortion attempts+ Of course, neither of these indicators
would prove that insurgents are truly motivated by resource-related grievances+
But these indicators would imply that the rebels believe that resource issues are
salient concerns in the population they wish to mobilize, and that raising these
issues will help them build support+
A third possibility is that resource wealth, if it is located on a country’s periphery
or in an area populated by an ethnic minority, will give local residents a ﬁnancial
incentive to establish a separate state, thus raising the risk of a civil war+ Le
Billon discusses this mechanism; Collier and Hoefﬂer offer it as well+20
It implies
the following:
H3: Resource wealth increases the probability of civil war by giving residents in
resource-rich areas an incentive to form a separate state.
17+ The looting mechanism suggests a second observable implication: if looting resource ﬁrms is
easier, or more sustainable, than looting nonresource ﬁrms, one should observe rebel groups gaining a
greater fraction of their ﬁnancing from the resource sector ~relative to its size in the economy! than
from other economic sectors+ This would be hard to test unless rebel organizations agree to have their
ﬁnances audited+
18+ Klare 2001, 208+
19+ See Gedicks 2001; Switzer 2001; Norimitsu Onishi, As Oil Riches Flow, Poor Village Cries
Out, New York Times, 22 December 2002, A1+ These theories might be seen as part of a larger literature
arguing that grievances, often proxied by poverty or inequality, tend to inﬂuence the danger of
civil war+ See, for example, Muller and Weede 1990; Auvinen 1997; Dudley and Miller 1998+
20+ See Billon 2001; Collier and Hoefﬂer 2002b+
Natural Inﬂuences and Civil War 41
If this mechanism is valid, one should observe in case studies that ~1! the conﬂict
is a separatist war; ~2! the conﬂict began after the separatist region was identiﬁed
as having exploitable resource wealth; and ~3! the rebel group discusses the unfair
distribution of resource wealth in its propaganda+ One would not necessarily observe
rebels attacking resource ﬁrms in this instance, because they should in principle
support resource extraction and may not wish to alienate companies working
in the sector+ To distinguish the second and third mechanisms from each other—
because both entail local grievances around resource extraction—I look for evidence
of the second mechanism only in nonseparatist conﬂicts, and the third
mechanism only in separatist conﬂicts+
Fearon and Laitin, among others, have suggested a fourth mechanism: that resource
wealth—in particular, oil—causes “state weakness,” which in turn increases
the probability of civil war+21
The claim that oil wealth inﬂuences the
character of the state has a long heritage among Middle East scholars: they commonly
suggest that oil wealth relieves governments of the need to levy taxes, which
in turn produces a state that is less responsive to its citizens+22
Karl developed this
argument further, suggesting that oil wealth also tends to impede the ability of
states to resolve social conﬂicts+23
Fearon and Laitin adopt this argument, and further
suggest that the absence of a “socially intrusive and elaborate bureaucratic
system to raise revenues” will make states more susceptible to civil war+24
This
claim could be stated as the following:
H4: Oil wealth increases the probability of civil war by weakening the state’s bureaucratic
capacity+
It is difﬁcult to know what the observable implications of this hypothesis are at
the case study level+ The mechanisms that may link oil to bureaucratic weakness—
and more problematically, bureaucratic weakness to subsequent conﬂict—could
be diffuse and subtle+ Advocates of this mechanism must further specify its logic
before it can be tested with case studies+
Duration
Natural resource wealth may inﬂuence the duration of civil war, independent of
its effects on the incidence of civil war+ There are three mechanisms that could
either lengthen or shorten a conﬂict, depending on how they occur; two of them
have implications that can readily be observed in case studies+
21+ Fearon and Laitin 2003+
22+ See, for example, Mahdavy 1970; Beblawi and Luciani 1987; Chaudhry 1997+ Although these
scholars discuss oil, their arguments may apply to natural gas as well+
23+ Karl 1997+
24+ Fearon and Laitin 2003, 81+
42 International Organization
The ﬁrst mechanism, once again, is looting+ Many observers—including scholars,
nongovernmental organizations ~NGOs!, and analysts from international
organizations—have suggested that resource wealth can lengthen a conﬂict if it
enables the rebels to fund themselves and hence continue ﬁghting instead of being
crushed or forced to the negotiating table+25
Many journalistic accounts of recent
wars in the mineral-rich states of Central and West Africa—including Liberia, Sierra
Leone, the Democratic Republic of Congo, and Angola—allude to this mechanism
when they claim that resources are “fueling” a conﬂict+
The mechanism entails two key assumptions: that the rebels are the weaker side;
and that strengthening the weaker side tends to lengthen conﬂicts+ In fact, there is
evidence from interstate conﬂicts to support the latter claim: Bennett and Stam
ﬁnd that international conﬂicts tend to last longer when the two sides have more
equal resources+26
If one assumes that when the weaker side in a civil war gains additional resources,
the conﬂict will be lengthened, one must also assume that when the stronger
side gains additional resources, the conﬂict will be shortened, by bringing about
a quicker victory or settlement+27
This implies the following:
H5: Resource wealth tends to increase (decrease) the duration of civil wars when
it provides funding to the weaker (stronger) side+
If this mechanism has occurred, there should be evidence that one side or the other
has raised money from the resource sector—through looting, extortion, or other
means—after the war began+ If both sides raised funds from the resource sector
simultaneously, I infer that the net effect has been to lengthen the conﬂict, based
on the conjecture that combat is likely to continue as long as the weaker party
does not run out of money+28
Some scholars have suggested a second duration-related mechanism: that resource
wealth discourages peace settlements, if wartime looting is sufﬁciently profitable
for either soldiers or their commanding ofﬁcers+ Sherman, for example,
suggests that
25+ See, for example, UN Panel of Experts 2000 and 2001; Sherman 2000; and the reports of Global
Witness, a London-based NGO, available at ^at www+globalwitness+org&+
26+ Bennett and Stam 1996+
27+ This raises several important problems for the coding of case studies+ First, a judgment must be
made about the relative military strength of the two sides before the resource is exploited, to avoid the
problem of endogeneity+ Second, it is necessary to restrict the analysis to contested resources+ Virtually
all governments derive at least a fraction of their revenue from the sale of natural resources; but I
only treat these as relevant if they are located in the contested terrain+ For civil wars that are national
in scope, I treat all resources as contested+
28+ This is less likely to be true in separatist conﬂicts than in nonseparatist conﬂicts+ As Fearon
points out, separatist and nonseparatist conﬂicts appear to have substantially different characteristics:
separatist conﬂicts tend to last longer, and often continue even when the separatist movement is at an
overwhelming ﬁnancial disadvantage+ Fearon 2004+
Natural Inﬂuences and Civil War 43
Rebel groups in Angola, Sierra Leone, Democratic Republic of Congo ~DRC!
and elsewhere enrich themselves through the sale or exchange of diamonds
+ + + economic interests not only shape the conﬂict, but, if the economic advantage
of ﬁghting outweighs that of peace, perpetuate it as well+29
Fearon makes a slightly different version of this argument, suggesting that the
presence of lootable resources could exacerbate principal-agent problems within
one or both of the armies by giving soldiers an incentive to accumulate personal
wealth instead of obeying their commanding ofﬁcers+30
This could make it harder
for negotiators to forge a binding, enforceable settlement+
Once again, this mechanism has a seldom-noticed corollary: if commanding ofﬁcers
believe that peacetime proﬁts would be greater than wartime proﬁts, it could
help induce them to reach a settlement+ Similarly, if soldiers believe that peace
would be more proﬁtable than war, they may refuse to ﬁght and force their commanders
to negotiate or surrender+ In hypothesis form, this “incentive” mechanism
and its corollary may be stated as the following:
H6: Resource wealth tends to increase (decrease) the duration of civil wars by
offering combatants a ﬁnancial incentive to oppose (support) a peace settlement+
This hypothesis is a slippery mechanism to observe in case studies+ It should not
be sufﬁcient to observe that war is proﬁtable for some combatants: this is virtually
inevitable when combat takes place on resource-rich territory, and it hardly proves
that the parties are deliberately lengthening the conﬂict+ One must instead determine
that one of two possible scenarios has transpired+ First, high-level ofﬁcers,
who have the ability to negotiate ~or block! a treaty, believe they would proﬁt more
if the war continues than if it comes to a negotiated end+ If this is occurring, one
should observe: ~1! evidence that resource looting is generating personal proﬁts for
high-level ofﬁcers; ~2! evidence that ofﬁcers would not be compensated in some
comparable way by a proposed peace treaty; and ~3! evidence that ofﬁcers chose
not to sign or adhere to an unproﬁtable peace accord+ Conversely, if resource wealth
is facilitating a peace accord, one should observe ofﬁcers who support a peace agreement
subsequently proﬁt from—or attempt to proﬁt from—the resource industry+
Alternatively, if resource wealth is lengthening a conﬂict through the incentives
it creates for the rank and ﬁle, one should observe the following: ~1! that at least
one army in the conﬂict suffers from major discipline problems; ~2! that disobedient
soldiers are personally beneﬁting from resource looting; and ~3! that these discipline
problems have made it harder for that party to sign or adhere to a peace
settlement+
29+ Sherman 2000, 699+
30+ Fearon 2004+
44 International Organization
If the same mechanism has shortened a conﬂict, one should again see: ~1! that
at least one army suffers from major discipline problems; ~2! that disobedient soldiers
are personally beneﬁting from resource looting; and ~3! that these problems
helped cause their army’s defeat or forced it to sign a peace agreement that it
might otherwise have opposed+
Finally, Fearon has suggested a third way in which resource abundance might
lengthen separatist conﬂicts+31
He speciﬁes a model in which the likelihood that
rebels will settle a conﬂict through an agreement for regional autonomy depends,
in part, on whether they believe the government is likely to adhere to it+ The model
suggests that if the region has resource wealth, the government is more likely to
renege on any such agreement, in order to gain access to future resource revenues+
Even if the government does not plan to renege, the rebels are more likely to expect
them to renege and hence should be more hesitant to sign a peace accord+32
The net result is that separatist conﬂicts over resource-rich regions should be unusually
difﬁcult to settle, because of the commitment problems that are aggravated
by resource wealth+ It may be phrased as the following:
H7: Resource wealth tends to increase the duration of separatist civil wars by making
it less likely that the government will adhere to a peace accord that gives the
region ﬁscal autonomy+
Unfortunately, this ﬁnal mechanism is hard to verify in case studies unless one
knows a great deal about the perceptions and motivations of rebel leaders+ For this
reason, I do not attempt to test it in these case studies+
Intensity
Resource wealth might also inﬂuence the intensity of civil conﬂicts, producing
more ~or fewer! conﬂict-related deaths over time+ Two mechanisms might bring
this about+ The most obvious mechanism is resource-related combat, in which opposing
armies battle over resource-rich territory+ Many observers of Africa’s recent
civil wars have suggested that combatants are “ﬁghting for control” of a
resource, implying the following:
H8: Resource wealth tends to increase the casualty rate during a civil war by
causing combatants to ﬁght for resource-rich territory that would otherwise have
little value+
31+ Ibid+
32+ The Fearon model includes the further suggestion that resource wealth discourages a peace settlement
when it provides rebels with a source of wealth during combat+ Because this is already covered
by the “looting” and “incentive” hypotheses ~H5 and H6!, I do not include it here+
Natural Inﬂuences and Civil War 45
I look for evidence in each case of resource-related battles, over sites that had
little or no intrinsic strategic value+
The second mechanism might reduce the intensity of civil wars+ Keen describes
a number of wars in which battleﬁeld opponents laid down their arms and cooperated
to extract resources;33
this suggests the following:
H9: Resource wealth tends to decrease the casualty rate during a civil war by
causing combatants to cooperate in resource exploitation.
If this type of cooperative plunder occurs, there should be reports of substantial
wartime trade and cooperation in resource exploitation between the two sides+ From
this, one might infer that the presence of resource wealth has reduced the casualty
rate+34
Case Selection
The thirteen cases in the sample were selected from the Collier-Hoefﬂer list of
thirty-six civil wars that began or continued between 1990 and 2000 ~see Table 1!+35
The cases were chosen on a “most likely” basis: the sample includes all civil wars
that occurred between 1990 and 2000 in which scholars, nongovernmental organizations,
or UN agencies suggested that natural resource wealth, or natural resource
dependence, inﬂuenced the war’s onset, duration, or casualty rate ~see
Table 2!+36
I employ a broad deﬁnition of “natural resources,” encompassing oil, gas, gemstones,
nonfuel minerals, timber, and agricultural commodities, including illicit
33+ Keen 1998+
34+ I am deliberately omitting a third possible mechanism: that resource looting enables one or both
combatants to arm themselves with more lethal equipment and hence kill each other at a faster rate+ It
is not obvious that greater military spending produces more lethal combat; moreover, I am already
assuming that resource revenues inﬂuence the duration of conﬂict, and do not wish to double-count+
35+ I made several amendments to the original Collier-Hoefﬂer list+ Collier and Hoefﬂer treat the
conﬂicts in four countries ~Afghanistan, Angola, Liberia, and Sierra Leone! as making up two successive
wars each+ Collier and Hoefﬂer 2002a+ For convenience, I treat each of them as a single conﬂict+
This has no bearing on my results+ I also—after consulting Collier and Hoefﬂer—changed their coding
for Indonesia, replacing the East Timor conﬂict ~which I regard as an invasion and temporary
occupation of a separate country, and hence not a civil war! with the Aceh conﬂict ~which meets their
strict deﬁnition of a civil war, generating at least one thousand battle-related conﬂicts in a calendar
year!+ I believe this corrects a miscoding in the original Singer-Small data set+
36+ I do not wish to claim that the sample is exhaustive: there may be other conﬂicts where resource
wealth has played an important but subtle—and perhaps, difﬁcult to observe—role+ In these
thirteen cases, however, there was prima facie evidence that natural resources had inﬂuenced the conﬂict+
46 International Organization
drugs+ While there are additional countries where commercially natural resources
may have inﬂuenced low-level conﬂicts, the sample is limited to cases that meet
the common deﬁnition of a civil war: a conﬂict between a government and an
TABLE 1. Civil wars in the 1990s
Country Primary exports/GDP Duration
Congo Republic 0.505 1997
Angola 0.476 1975–2002
Liberia 0.393 1989–96
Iraq 0+22 1985–92
Indonesia 0.219 1976–
Sri Lanka 0+211 1983–
El Salvador 0+209 1979–92
Algeria 0+179 1991–
Nicaragua 0+166 1982–90
Philippines 0+146 1972–96
Congo, Dem. Rep. 0.141 1997–99
Congo, Dem. Rep. 0.141 1996
Peru 0.13 1982–96
Sierra Leone 0.12 1991–2000
Russia 0+117 1999–
Yemen 0+105 1990–94
Somalia 0+103 1988–92
Mozambique 0+099 1976–92
Colombia 0.094 1984–
Sudan 0.086 1983–
Myanmar/Burma 0.078 1983–95
Russia 0+066 1994–96
Ethiopia 0+065 1974–91
Burundi 0+064 1991–
Cambodia 0.052 1970–97
Rwanda 0+047 1990–94
Turkey 0+038 1991–
Lebanon 0+036 1975–92
Afghanistan 0.033 1992–2001
Yugoslavia 0+032 1990–92
India 0+018 1984–94
Azerbaijan N+A+ 1991–94
Bosnia N+A+ 1992–95
Georgia N+A+ 1991–93
Tajikistan N+A+ 1992–94
Yugoslavia N+A+ 1998–99
Source: Adapted from Collier and Hoefﬂer 2001+
Note: The “primary exports0GDP” variable is the Collier-Hoefﬂer measure of primary
commodities as a fraction of GDP preceding the onset of conﬂict+ The cases
in the sample are listed in bold+ N+A+ ϭ not applicable+
Natural Inﬂuences and Civil War 47
organized rebel movement that produces at least one thousand battle-related
deaths+37
The thirteen cases vary by conﬂict type, and include three separatist wars
~Sudan, Indonesia, and Burma! and ten nonseparatist wars ~Afghanistan, Angola,
Cambodia, Colombia, Republic of Congo, Liberia, Peru, Sierra Leone, and two
successive wars in the Democratic Republic of Congo @DRC#!+
If I were trying to determine whether resource wealth is correlated with civil
war, this would be the wrong set of cases to look at, because in these cases such a
link is likely because of the selection method+ But this is not my concern: the
resource dependence–civil war correlation has already been established by the
large-N studies discussed above+ What I wish to determine are the causal processes
that link the variables together+
The “most likely” method of case selection enables me to carry out three types
of analysis+ First, if the causal mechanisms that others have proposed can be illustrated
in these thirteen cases, I may deem them “plausible+” Second, and more
powerfully, if a purported causal mechanism is not observed in this set of cases, I
can infer that it is unlikely to be valid more generally+ Similarly, by observing
whether a mechanism is absent in all of the separatist or nonseparatist conﬂicts in
the sample, I can make inferences about the mechanism’s validity in each sub-
37+ Low-level conﬂicts that may be linked to natural resources include the Bougainville rebellion in
Papua New Guinea; the Cabinda conﬂict in Angola; the West Papua rebellion in Indonesia; the conﬂict
in Senegal’s Casamance region; and the independence movement in Western Sahara+ For a more extensive
discussion of these and other cases, see Le Billon 2001+
TABLE 2. Civil wars linked to resource wealth, 1990–2000
Country Duration Resources
Afghanistan 1992–2001 Gems, opium
Angola 1975–2002 Oil, diamonds
Burma 1983–95 Timber, tin, gems, opium
Cambodia 1978–97 Timber, gems
Colombia 1984- Oil, gold, coca
Congo Republic 1997 Oil
Congo, Dem+ Rep+ 1996 Copper, coltan, diamonds, gold, cobalt
Congo, Dem+ Rep+ 1997–99 Copper, coltan, diamonds, gold, cobalt
Indonesia (Aceh) 1976- Natural gas
Liberia 1989–96 Timber, diamonds, iron, palm oil, cocoa, coffee,
marijuana, rubber, gold
Peru 1982–96 Coca
Sierra Leone 1991–2000 Diamonds
Sudan 1983- Oil
Note: Separatist conﬂicts are listed in italics+
48 International Organization
category of conﬂicts+ Finally, I can use the cases to develop new hypotheses about
causal mechanisms+
The most-likely research design does not permit me to make cross-national inferences
within my sample ~except for comparisons between two subcategories of
cases, the separatist and nonseparatist conﬂicts!; nor can I make valid inferences
for the larger population of states about the frequency, or relative weight, of the
causal mechanisms I observe+
Because the sample only includes cases in which resource wealth is likely to
have an effect on the onset or duration of a civil war, I am unlikely to ﬁnd—and
indeed, do not ﬁnd—evidence that the resource–civil war correlation is spurious,
or that civil wars cause resource dependence instead of the reverse+ But by determining
whether the resource wealth–civil war link is internally valid in a substantial
number of cases, I can ease ~or heighten! suspicions that the correlation is
spurious or reversed+
Results from Case Studies
The causal mechanisms observed in the thirteen cases are summarized in Tables 3
through 6+38
Overall, there is evidence in ﬁve of the thirteen cases that resource
wealth made conﬂict more likely, and in eight of the thirteen cases that resource
38+ I conducted one of the case studies—Indonesia—using primary sources and ﬁeld work in June–
July 2000+ I based the other twelve case studies on secondary sources, including academic studies,
interviews with country experts, UN reports, journalistic accounts, and reports from nongovernmental
organizations+ When data are missing or ambiguous, I note this in the text+
TABLE 3. Summary of ﬁndings
Onset Duration Intensity
Afghanistan No Longer None
Angola No Longer Mixed
Burma No Mixed Mixed
Cambodia No Mixed Mixed
Colombia No Longer Mixed
Congo Republic Yes Shorter None
Congo, Dem+ Rep+ I No Shorter None
Congo, Dem+ Rep+ II Yes Longer Mixed
Indonesia Yes None Worse
Liberia No Longer Mixed
Peru No Longer Worse
Sierra Leone Yes Longer Mixed
Sudan Yes Longer Mixed
Natural Inﬂuences and Civil War 49
wealth made conﬂict last longer+ Within the sample, the inﬂuence of resource wealth
on conﬂict intensity varied greatly—appearing to increase the casualty rate in two
cases, having a mixed effect in eight, and no effect in three+
The most striking ﬁnding may be that there is no evidence in the sample of the
looting mechanism, and little if any evidence of the grievance mechanism+ There
were several notable differences between separatist and nonseparatist conﬂicts+ Resources
also contributed to the onset, duration, and intensity of conﬂict in four
ways that were not predicted by the seven hypotheses tested+
Incidence of Conﬂict: Evidence
Resource wealth contributed to the outbreak of conﬂict in ﬁve of the thirteen cases:
in two cases ~Indonesia and Sudan!, resource wealth appeared to create an incentive
for a separatist rebellion; and in three cases ~Congo Republic, DRC II, and
Sierra Leone! resources seemed to contribute to the outbreak of conﬂict in ways
that were not predicted by the hypotheses ~see Table 4!+ To account for these latter
cases, I develop two new hypotheses in the following section+
There were no cases of the looting mechanism ~H1! that Collier and Hoefﬂer
suggest: in these thirteen cases, nascent rebel groups never gained funding before
the war broke out from the extraction or sale of natural resources, or from the
extortion of others who extract, transport, or market resources+ If interpreted strictly,
the Collier-Hoefﬂer looting mechanism gains no support from these cases+ While
TABLE 4. Origins of conﬂict
Looting Grievance Separatism Other
Afghanistan No No — No
Angola No No — No
Burma No — No No
Cambodia No No — No
Colombia No No — No
Congo Republic No No — Yes†
Congo, Dem+ Rep+ I No No — No
Congo, Dem+ Rep+ II No No — Yes*
Indonesia No — Yes No
Liberia No No — No
Peru No No — No
Sierra Leone No No? — Yes*,†
Sudan No — Yes No
Note: The “grievance” mechanism is ~by deﬁnition! only observable in the ten nonseparatist
conﬂicts; and the “separatism” mechanism is observable in the three separatist
conﬂicts+ * Unanticipated mechanism: foreign intervention+ † Unanticipated mechanism:
sale of future rights to war booty+
50 International Organization
there is abundant evidence that rebel groups engage in looting after a war begins
~as discussed below!, in this sample no rebel group funded its startup costs from
the resource sector+
There was also no evidence that the grievance mechanism ~H2! has led to civil
war, although the case of Sierra Leone is ambiguous+ In general, however, no nonseparatist
civil wars were associated with complaints about land expropriation,
environmental degradation, insufﬁcient employment opportunities, or pressures
caused by labor migration to resource-rich areas+ This does not suggest that these
grievances are illusory: they are real and ubiquitous+ But they never appeared to
contribute to the outbreak of a nonseparatist civil war+
There may be an exception to this pattern: the case of Sierra Leone, where the
evidence is ambiguous+ The war in Sierra Leone began in March 1991 when the
Revolutionary United Front ~RUF! ﬁrst crossed the border from Liberia+ The following
January, RUF conducted operations in diamond-rich southeastern Sierra
Leone; beginning in September 1992, RUF and government troops fought for control
of the diamond-rich areas+
The case of Sierra Leone exhibits one of the indicators of a grievance-based
conﬂict: RUF propaganda complained about resource exploitation, railing against
“the raping of the countryside to feed the greed and caprice of the Freetown elite
and their masters abroad+”39
Whether or not it met the second criteria—attacking
resource ﬁrms—is uncertain: although RUF conducted operations in Sierra Leone’s
diamond-producing areas and drove out many Lebanese diamond traders,
these operations may have simply been part of RUF’s diamond-looting tactics+
Hence it is unclear whether resource grievances helped initiate the war in Sierra
Leone+40
Even if Sierra Leone is coded as an example of a “grievance” mechanism,
it is notable that the grievances exploited by the rebel group concerned the
distribution of resource wealth, not land expropriation, labor migration, environmental
damage, or lack of job opportunities+
The sample includes three separatist civil wars; in two of them ~Indonesia and
Sudan! there is evidence of the “separatist” mechanism ~H3!+ The Indonesian civil
war occurred in the northwest province of Aceh+ The rebel group—widely known
as GAM ~Gerakan Aceh Merdeka, Aceh Freedom Movement!—started in 1976,
shortly before a large natural gas facility began operations+ GAM’s 1976 “Declaration
of Independence” denounced the Indonesian government for stealing Aceh’s
resource revenues, but GAM did not criticize the natural gas facility itself, or Mobil
~now ExxonMobil!, which operates the facility+41
One of its ﬁrst acts was to attack
39+ RUF, quoted in Richards 1996, 27+ Specialists disagree as to whether the RUF leadership actually
believed these charges—see Richards 1996—or simply used this rhetoric for recruitment purposes—
see Abdullah 1998+ For the purposes of this analysis, however, this dispute is irrelevant+
40+ On RUF’s 1992 activities in the diamond-rich areas, see Richards 1996; Reno 1998; and Abdullah
and Muana 1998+
41+ Indeed, the founder of GAM, Hasan di Tiro, was a businessperson who failed in his effort to
win a bid for a work contract at the natural gas facility+ Robinson 1998+
Natural Inﬂuences and Civil War 51
the plant+42
During the subsequent conﬂict, GAM propaganda often claimed that
if Aceh were independent, its citizens would be as wealthy as their neighbors
in the tiny oil-rich sultanate of Brunei+ Although the claim was wildly
exaggerated—by at least an order of magnitude—it became widely accepted as
fact within the province+
The war in the Sudan began in 1983, when Sudanese President Gaafar Numeiry
took a series of measures that upset the delicate balance between the predominantly
Muslim north and the heavily Christian and Animist south; among these
measures was his decision to place newly discovered oil in the country’s south
under the jurisdiction of the north, and to build an oil reﬁnery in the north instead
of the south+ The Sudan People’s Liberation Army ~SPLA! subsequently complained
that the north was stealing the resources of the south, including oil; demanded
that work cease on a pipeline to take oil from the south to the reﬁnery in
the north; and in February 1984, attacked an oil exploration base, killing three
foreign workers and bringing the project to a halt+43
To summarize, there is good evidence that natural resources helped initiate two
of the three separatist conﬂicts in this sample; however, there is no evidence of a
looting mechanism, and little or no evidence of a grievance mechanism+ Resource
wealth apparently led to conﬂict through two unanticipated mechanisms, which
are discussed in the next main section+ Illicit drugs were not linked to the origins
of any of the thirteen wars+
Duration of Conﬂict: Evidence
Resource wealth appears to have inﬂuenced the duration of ten of the thirteen
conﬂicts: it lengthened eight, shortened two, had a mixed effect in two, and had
no effect in one ~see Table 5!+ Once again, an unanticipated mechanism also inﬂuenced
several conﬂicts+
While looting played no role in the initiation of these thirteen conﬂicts, it played
a role in the duration of ten conﬂicts ~H5!+ In other words, in these thirteen cases,
rebel groups only started to loot resources after the conﬂicts began+ In nine of the
ten cases, the looted commodity was a type of resource that can be easily extracted,
or cultivated, by small groups of unskilled workers—mostly gemstones
~ﬁve cases!, drugs ~four cases!, or timber ~two cases!+
In two cases, however, rebels have used extortion and kidnapping to raise money
from a more difﬁcult-to-loot commodity+ In Colombia and Sudan, insurgents have
been able to raise money by blowing up oil pipelines and ransoming kidnapped
oil workers+ In both cases, the rebels have capitalized on the precarious geography
of their country’s oil industry by sabotaging pipelines that stretch for hundreds of
miles, crossing territory where they have a strong presence+ In Colombia, two in-
42+ Robinson 1998+
43+ See O’Ballance 2000; Anderson 1999+
52 International Organization
dependent rebel movements bombed the pipelines ninety-eight times in 2000+ Together,
they have used these attacks to extort an estimated $140 million annually;
this windfall has enabled one group, the National Liberation Army ~ELN!, to grow
from fewer than forty members to at least 3,000+44
There was evidence in two cases ~DRC II and Liberia! that resource wealth
lengthened a conﬂict through an incentive mechanism ~H6!, giving combatants an
economic incentive to avoid signing, or adhering to, a peace agreement+ In three
other cases ~Congo Republic, Cambodia, and Burma!, however, the incentive mechanism
had the opposite effect, giving combatants an inducement to settle+
The Liberian civil war lasted from December 1989 to August 1996+ Between
June 1990 and August 1996 the combatants signed fourteen peace accords, thirteen
of which failed+ One important reason for these failures was that the warring
parties—or at least, signiﬁcant factions within them—feared they would lose access
to Liberia’s resource wealth+ This fear reduced the incentive of the parties to
comply with the terms of the agreements+ The failure of the 1993 Cotonou accord—
signed by the parties under heavy international pressure—provides one of the sharpest
illustrations+ Almost immediately after the agreement was signed, the signatories
created nominally independent surrogate groups that—because they were not
signatories—could carry on with proﬁtable wartime looting+ This practice contributed
to the accord’s collapse+45
It also implies that combatants subverted the treaty
so they could continue their looting, thus lengthening the conﬂict+
In the war that plagued the DRC beginning in 1998—which has both the qualities
of a civil war and an international war—the proﬁtability of resource looting
44+ Dunning and Wirpsa forthcoming+
45+ See Alao et al+ 1999; Ellis 1999+
TABLE 5. Duration of conﬂict
Looting Incentive Futures Net effect
Afghanistan Yes No No Longer
Angola Yes No Yes Longer
Burma Yes Yes* No Mixed
Cambodia Yes Yes* No Mixed
Colombia Yes No No Longer
Congo Republic No Yes* No Shorter
Congo, Dem+ Rep+ I No No Yes* Shorter
Congo, Dem+ Rep+ II Yes Yes Yes Longer
Indonesia No No No None
Liberia Yes Yes No Longer
Peru Yes No No Longer
Sierra Leone Yes No Yes Longer
Sudan Yes No No Longer
*Made the conﬂict shorter.
Natural Inﬂuences and Civil War 53
for foreign governments, rebel militias, and individual ofﬁcers substantially reduced
their incentive to end the conﬂict+ Even though a peace accord was signed
in Lusaka in July 1999, it was not implemented until 2002, in part because it forced
foreign combatants to withdraw from the DRC, which hampered their ability to
siphon off the country’s remarkable resource wealth+46
Conversely, the 1997 civil war in the Congo Republic may have been shortened
by the combatants’ agreement to share the oil revenues+47
Similarly, the Burmese
government reached settlements with the Shan State Army ~in 1989! and the Kachin
Independence Army ~in 1994! after agreeing to jointly exploit the opium, timber,
and precious stones in rebel-held territory+ Although rebel groups already controlled
these resources, the agreements made it easier for them to attract new investment
in, process, and export their goods+48
The Cambodia civil war was also shortened after 1996 when the country’s resource
wealth gave a faction in the rebel group ~the Khmer Rouge! an incentive to
defect to the government+ Until 1995, income from the sale of timber and gemstones
had helped fund the Khmer Rouge and, hence, lengthened the civil war+
But in 1996 Ieng Sary, one of the Khmer Rouge’s top ofﬁcials, surrendered to the
government along with 4,000 soldiers under his command+ As part of the surrender
agreement, he was allowed to retain his troops and keep control of a gem-andtimber-rich
area near the Thai border+ The Khmer Rouge never recovered from his
defection, and by 1998 the Khmer Rouge had collapsed, bringing about an end to
the war+49
There was little evidence of an incentive mechanism in two cases where others
suspect it exists: Angola and Sierra Leone+50
In both cases, rebel leaders generated
enormous sums from resource looting; this may have led some observers to falsely
infer that resource wealth caused the rebels to prefer war to peace+ But in each
case, peace negotiators anticipated this problem and drafted accords that would
enable rebel leaders to continue getting rich—or get even richer—in peacetime+
Both the 1999 Lomé accord in Sierra Leone, and the 1994 Lusaka Protocols in
Angola, offered to place the rebel leader ~Foday Sankoh in Sierra Leone and Jonas
Savimbi in Angola! in charge of the country’s natural resources under a unity
government+ Peace would also allow the minerals sector in each country to expand
by enabling abandoned mines to reopen and new ones to develop, presenting
the rebels with new opportunities for enrichment+51
In both cases, these peace accords
failed, but for reasons other than the lure of wartime looting+
46+ See ICG 2000; and UN Panel of Experts 2001 and 2002+ The foreign armies withdrew in 2002
only after making arrangements—by establishing joint ventures, and by using local militias that acted
as their surrogates—to continue proﬁting from the DRC’s mineral wealth+ UN Panel of Experts 2002+
47+ Pierre Englebert, Pomona College, personal communication, October 2001+
48+ Lintner 1999+
49+ See Brown and Zasloff 1998; Le Billon 2000+
50+ Sherman 2000+
51+ See Le Billon 1999; Vines 1999+
54 International Organization
In sum, there is evidence to support both of the hypothesized mechanisms: the
looting mechanism ~H5! appeared to lengthen ten of the thirteen conﬂicts and the
incentive mechanism ~H6! ostensibly lengthened two+ When both the looting and
incentive effects are aggregated, resource wealth prolonged eight conﬂicts, shortened
two, had a mixed effect in two, and had no impact in one+52
The analysis
also suggests, however, that analysts should approach claims about the importance
of the incentive mechanism skeptically: it may have lengthened two conﬂicts,
but it shortened three others, and there was no evidence of it in several
other conﬂicts where some have suggested it operates+
Intensity of Conﬂict: Evidence
There was evidence of both hypothesized effects—resource battles and cooperative
plunder—in the thirteen cases ~see Table 6!+ Often, both mechanisms appeared
in the same war+ There was, once again, evidence of an unexpected
mechanism inﬂuencing the intensity of conﬂicts+ Collectively, resource wealth
heightened the casualty rate in two wars, had no effect in three wars, and had a
mixed impact in eight wars+53
Resource battles ~H8! occurred in nine of the thirteen cases, as combatants fought
for control of areas rich in alluvial gemstones ~Sierra Leone, Liberia, Cambodia!,
52+ I determine the net effect as follows: if a case exhibited only conﬂict-lengthening, or conﬂictshortening,
effects, I judge the net effect as “longer” or “shorter,” respectively+ If a case has both
conﬂict-lengthening and conﬂict-shortening effects, I list the net effect as “mixed+”
53+ I evaluate the net effect as follows: if a case exhibited only conﬂict-enhancing, or only conﬂictreducing
effects, I list the net effect as “worse” or “better,” respectively+ If there are both conﬂictenhancing
and conﬂict-reducing effects, I judge the net effect to be “mixed+”
TABLE 6. Intensity of conﬂict
Battles Plunder Repress Net effect
Afghanistan No No No None
Angola Yes Yes No Mixed
Burma Yes Yes No Mixed
Cambodia Yes Yes No Mixed
Colombia Yes Yes No Mixed
Congo Republic No No No None
Congo, Dem+ Rep+ I No No No None
Congo, Dem+ Rep+ II Yes Yes No Mixed
Indonesia No No Yes Worse
Liberia Yes Yes No Mixed
Peru Yes No No Worse
Sierra Leone Yes Yes No Mixed
Sudan Yes Yes Yes Mixed
Natural Inﬂuences and Civil War 55
drug ﬁelds and processing plants ~Peru, Burma!, oil pipelines that traveled over
disputed lands ~Colombia, Sudan!, mines ~DRC I and II, Liberia!, and commercially
valuable forests ~Cambodia, Liberia!+
Yet in eight of these nine cases, combatants intermittently cooperated in exploiting
the same resources they fought over ~H9!+ In four cases ~Sierra Leone, Liberia,
DRC II, and Cambodia! there were long periods in which the major parties
more or less ceased their combat and entered a kind of commercial equilibrium+
Even in extraordinarily bitter wars such as the one in Sudan, proﬁtable alliances
were often struck between groups on opposing sides—in this case, to guard the
pipeline and oilﬁelds that the rebels had long opposed+54
The only war that featured resource battles but not cooperative plunder was in
Peru, between the government and the hard-line Maoist group, Sendero Luminoso+
Beginning around 1983, Sendero Luminoso controlled a large coca-producing
area in Peru’s Upper Huallaga Valley; they also periodically clashed with both
government forces and a rival guerrilla group over control of the coca trade+ Sendero
Luminoso’s failure to cooperate with the Peruvian military in coca production
likely reﬂected both their highly disciplined and ideological character, and
their ability to ﬂy coca paste directly from the Upper Huallaga Valley to Colombia
without passing through government-controlled territory or airspace+
Resource battles and cooperative plunder seem to be closely linked+ In the eight
cases where both occurred, it was impossible to judge which of these two effects
had the greatest impact+ I hence infer that they at least partially offset each other
and produced a “mixed” effect on the intensity of combat+55
Unexpected Mechanisms
In these thirteen cases, not all of the resource-conﬂict correlations could be accounted
for by the seven hypothesized mechanisms; I also identiﬁed four additional
mechanisms at work+ Two inﬂuenced the onset of conﬂict, one inﬂuenced
conﬂict duration, and one affected the intensity of conﬂict ~see Figure 2!+
In four of the thirteen cases, natural resource wealth helped trigger conﬂicts in
two ways that were not predicted by the hypotheses+ The ﬁrst was by encouraging
interventions from neighboring powers: in Sierra Leone, and the DRC II war, foreign
forces decided to support nascent rebel groups against incumbent governments,
in part, to gain access to natural resource wealth+
54+ ICG 2002+
55+ In ﬁve of these nine cases ~Sudan, Sierra Leone, Liberia, DRC II, and Cambodia!, resources
appeared to help fracture rebel or government alliances based on ethnic, religious, or ideological grounds,
and create new alliances based on commercial grounds+ It was difﬁcult to judge whether these fractures
inﬂuenced the casualty rate; moreover, it is not possible to know if resource wealth leads to an
unusually high rate of alliance fracture without examining alliance stability in comparable resourcepoor
conﬂicts+
56 International Organization
In Sierra Leone, Liberia’s Charles Taylor helped organize and support the 1991
RUF invasion to gain access to Sierra Leone’s diamond ﬁelds+56
Similarly, the
Ugandan and Rwandan governments decided to organize, and ﬁght alongside, rebels
in the DRC partly because of the DRC’s resource wealth+ The UN Panel of Experts
found that Uganda’s decision to enter the war was inﬂuenced, in part, by at
least three ﬁgures who were eager to proﬁt from the occupation of resource-rich
parts of the DRC+57
In Rwanda, the government’s decision to back an incursion
was inﬂuenced by the belief—which was subsequently proved correct—that resource
looting would help offset the cost to the government of the invasion, which
might have otherwise been prohibitive+ Once inside the DRC, the Rwandan army
established well-disciplined procedures for extracting Congolese resources and using
them to fund the military effort+58
Based on these two cases, a new hypothesis might be stated as the following:
H10: Resource wealth increases the likelihood of civil war by increasing the probability
of foreign intervention to support a rebel movement.
The second and more surprising mechanism entailed the sale, by rebel groups,
of what might be called “booty futures”—the right to exploit mineral resources
that the seller has not yet captured+ In three cases ~Congo Republic, Sierra Leone,
and possibly Liberia!, rebel groups that had no resources to sell, but had a chance
of securing them in combat, were able to sell future mineral rights to foreign ﬁrms
or neighboring governments+ The rebels then used the proceeds from the sale of
booty futures to pay soldiers and buy arms, and thus gain the capacity to capture
the promised resource+
The special danger of selling booty futures comes from its self-fulﬁlling properties+
If the rebel group was unable to sell the future right to exploit the resource,
56+ See Abdullah 1998; UN Panel of Experts 2000+
57+ UN Panel of Experts 2001+
58+ UN Panel of Experts 2001 and 2002+
FIGURE 2. Unanticipated mechanisms
Natural Inﬂuences and Civil War 57
it might not have the funds it needs to capture the resource itself+ Selling the future
right to the resource makes its seizure possible+ Without the futures market,
the rebel offensive—and perhaps the conﬂict itself—would be less likely+59
In the Congo Republic, a former president, Denis Sassou-Nguesso, received $150
million from the French oil company, Elf-Aquitaine, to help him defeat the incumbent
president, Pascal Lissouba, either by force or through a national election; the
payment was clearly meant to ensure Elf’s access to Congolese oil in a future
Sassou government+60
The election never took place+ Instead, Sassou and Lissouba
fought a four-month war that destroyed much of Brazzaville and cost 10,000
lives, eventually leaving Sassou in charge+61
Something similar occurred in Sierra Leone, when RUF launched its 1991 invasion+
RUF received material support from a variety of sources; they included
the Liberian leader, Charles Taylor, and a Sierra Leone businessperson who had
recently been forced out of the diamond industry+62
There is circumstantial evidence
that the RUF leadership traded this ﬁnancial support for future diamond
rights—in effect, using informal mining futures to purchase their assistance+63
The notion of “booty futures,” in hypothesis form, might be stated as the
following:
H11: Resource wealth increases the probability of civil war by enabling rebel groups
to sell future exploitation rights to minerals they hope to capture.
A third unanticipated mechanism—once again, the sale of booty futures—
inﬂuenced the duration of three conﬂicts: Sierra Leone, Angola, and the DRC+
During the war in Sierra Leone, the government saved itself from defeat twice
by selling off the right to exploit diamond ﬁelds that it did not yet control+ In
March 1995, RUF had taken control of the country’s main diamond ﬁelds and
advanced to within twenty miles of the capital+ To stave off defeat, the government
sold future mining rights to the Kono diamond ﬁelds—then in rebel hands—to
Branch Energy, a South African company; the government then used the proceeds
to hire a South African mercenary ﬁrm, Executive Outcomes, to beat back the
59+ In principle, rebels could sell futures for any type of war spoils, not just mineral resources+ In
practice, minerals appear to be the only commodities for which future exploitation rights have been
sold—perhaps because they are easier to exploit under wartime conditions+
60+ Elf had lost its oil contract under the government of Lissouba, Sassou’s rival+
61+ Martine-Renée Galloy and Marc-Éric Gruénai, Fighting for Power in the Congo, Le Monde
Diplomatique, November 1997+
62+ See UN Panel of Experts 2000; Reno 1998+
63+ There may have been a similar sale of booty futures in Liberia, although the evidence is unclear+
The Liberian civil war began on Christmas Eve 1989, when Taylor led one hundred troops from
the NPFL into Liberia from neighboring Côte D’Ivoire+ According to Ellis, just before the invasion
Taylor met with business interests who hoped to gain access to Liberia’s iron ore and timber; Taylor
reportedly received “sympathetic attention” from them+ Ellis is uncertain, however, whether these business
interests actually helped ﬁnance Taylor’s efforts+ Ellis 1999+
58 International Organization
RUF offensive and recapture the mortgaged diamond ﬁelds+64
Just two years later,
a deposed president, Ahmad Tejan Kabbah, sold $10 million in diamond futures to
a Thai banker; Kabbah used the revenues to hire Sandline, a London-based mercenary
ﬁrm, to take back the capital and the diamond ﬁelds+65
In each case, the
sale of future mineral rights helped prolong the conﬂict+
The sale of booty futures also lengthened the Angolan conﬂict+ In 1992–93, the
rebel group UNITA waged an offensive that brought more than 70 percent of the
country—including all of its diamond-rich areas and the northern oil town of
Soyo—under its control+ To fund a counteroffensive, the government sold off future
exploitation rights to both oil ﬁelds ~still under the government’s control!,
and diamond areas ~some of which were under rebel control!+ In one deal, the
government hired International Defence and Security ~IDAS!, a private military
services company, to retake the diamond ﬁelds near the DRC border; the government
paid IDAS with a share of the contested diamonds+66
In the 1996–97 conﬂict in the DRC, the sale of booty futures most likely shortened
the conﬂict because it generally beneﬁted the stronger side+ In this conﬂict,
the rebel organization—the Alliance of Democratic Forces for the Liberation of
Congo0Zaïre ~ADFL!, led by Laurent-Desiré Kabila—received a huge resource
windfall after it became clear that it was defeating the government in combat+67
In
April 1997, Kabila signed an $885 million contract with American Mining Fields,
a U+S+ ﬁrm intent on exploiting Congolese copper, cobalt, and zinc+68
Around the
same time, the minerals parastatal, Miniére de Bakangwa, switched its support
from the government to ADFL, offering Kabila both cash and the use of its aircraft
ﬂeet+69
This support helped Kabila move his troops across the country to the
capital, Kinshasa, and take over the Congolese government+ Since Kabila’s April
1997 sale of mineral futures helped strengthen the hand of the winning side, I
infer that it helped bring about a swifter end to the war+70
These three cases suggest the following:
H12: Resource wealth tends to increase (decrease) the duration of civil wars by
enabling the weaker (stronger) side to earn revenues by selling future exploitation
rights to minerals they hope to capture+
64+ Hirsch 2001+
65+ Africa Conﬁdential 2001+
66+ See Peleman 2000; Vines 1999+
67+ The ADFL was led by the Rwandan army and backed by the Ugandan army, who were principally
concerned with eliminating the threat created by the exiled Rwandan government in eastern Congo+
The exiled Rwandan government was led by ethnic Hutus and was responsible for the 1994 Rwandan
genocide+ Kabila was a longtime political ﬁgure who had opposed Mobutu since the early 1960s+
68+ The $885 million ﬁgure represented future investment+ However, it is customary in large deals
for the company to also pay a signing bonus, which would have augmented the AFDL’s revenues+ The
Kabila government later reneged on the contract+
69+ See Howard W+ French, The Great Gold Rush in Zaire, New York Times, 18 April 1997, A6;
Reed 1998+
70+ For more details on this booty futures market, see Ross 2002+
Natural Inﬂuences and Civil War 59
In two of the cases ~Indonesia and Sudan!, a ﬁnal unexpected effect appeared to
link resource wealth with the intensity of combat; the mechanism might be called
“preemptive repression+” In each case, a government facing a small, separatist rebellion
in a resource-rich area acted strategically to protect its control of the resource,
by using terror against the region’s population+ Had the region been
resource-poor, the governments might have responded less harshly to these challenges,
producing fewer casualties+
In the Indonesian case, the government imposed martial law, terrorized villages,
and carried out egregious human rights abuses in Aceh between 1990 and
1998 to crush a small independence movement that had claimed that the government
was unjustly appropriating Aceh’s resource wealth+71
By the end of 1991, all
of the group’s active members had been captured, killed, or driven into exile; yet
martial law, and widespread repression, continued until 1998+ There is evidence
that the harshness of the repression was, in part, because of Aceh’s natural gas
deposits: the government gave the military an exceptionally large role in planning
and running the natural gas project; it placed the Military Operations Command
for Aceh near the gas facility, instead of in the province’s capital; and ofﬁcers
assigned to protect the plant were involved in the torture and execution of Acehnese
in neighboring areas+72
Ironically, the repression backﬁred, generating a ﬂood
of new recruits for the rebels after the dictator Suharto fell, leading to a renewal
of the conﬂict in 1999+
In Sudan, the preemptive repression has been severe: beginning in the late 1990s,
the government attempted to create a cordon sanitaire around a 936-mile pipeline
that brings oil from the rebellious south to a port in the north+ Since early 1999,
the government has used summary executions, rape, ground attacks, helicopter gunships,
and high-altitude bombing to force tens of thousands of people from their
homes in the oil regions+73
There has often been a close correlation—both temporally
and geographically—between oil exploitation and extreme repression+ In one
well-documented case, Lundin Oil ~a Swedish ﬁrm! discovered a major oil reserve
in April 1999 at Thar Jath; a month later, government troops displaced tens
of thousands of people from the area+ When ﬁghting nonetheless erupted ten months
later around the Thar Jath site, Lundin Oil suspended operations while government
troops used aerial bombing, the burning of villages, and summary executions
to depopulate a large area around the oilﬁeld+ Shortly after depopulation was
completed, Lundin Oil resumed operations+74
Preemptive repression only occurred in separatist conﬂicts, at least within this
sample+ This may be because governments are more willing to take repressive
measures against peripheral minority groups than members of the majority popu-
71+ In 1990–91, the independence movement had between 200 and 750 active members+ Ross 2003a+
72+ Ross 2003a+
73+ Amnesty International 2000+
74+ Christian Aid 2001+
60 International Organization
lation+ Perhaps governments are more likely to expect trouble when resource exploitation
occurs in regions with separatist aspirations than when it occurs in other
regions+ In either case, the Indonesian and Sudanese conﬂicts suggest a ﬁnal
hypothesis:
H13: Resource wealth tends to increase the casualty rate during a separatist civil
war by giving the government an incentive to react to small challenges with unusually
harsh countermeasures+
Conclusion
This article discusses several hypotheses about how resources may inﬂuence a
conﬂict; speciﬁes their observable implications; and reports which of these implications
can be observed in a “most likely” sample of thirteen cases+ This method
facilitates three types of analysis: if the hypothesized causal mechanisms can be
observed in these thirteen cases, they may be considered plausible; if they cannot,
the mechanisms are unlikely to be valid more generally; and the cases may be
used to develop new hypotheses+
Collectively, these three types of analysis have led to eight notable ﬁndings+
First, there is good evidence in the thirteen cases that natural resource wealth is
causally linked to civil conﬂict+ I cannot dismiss the possibility that the natural
resource–civil war correlation is, in part, spurious, or that causality runs in the
opposite direction+ Indeed, there is good evidence in at least one case ~Angola!
that the onset of civil war made the economy more dependent on resource ex-
ports+75
But in these thirteen conﬂicts, there is strong evidence that resource wealth
has made conﬂict more likely to occur, last longer, and produce more casualties
when it does occur+
Second, while oil, nonfuel minerals, and illicit drugs appear to inﬂuence conﬂict,
other types of primary commodities—notably legal agricultural commodities—
seem to be unrelated to civil war, at least in these thirteen cases+ Scholars have
found statistical correlations between conﬂict and all types of primary commodi-
ties,76
minerals,77
oil,78
and lootable contraband+79
These cases suggest that the
latter three categories are indeed causally linked to violent conﬂict, and that the
primary commodities variable should be pared down to include only oil, nonfuel
minerals ~including gemstones!, and ~if possible! illicit drugs+
The third ﬁnding is that two of the most widely cited causal mechanisms, the
looting and grievance mechanisms, do not appear to be valid+ There was no evi-
75+ Minter 1994+
76+ Collier and Hoefﬂer 1998 and 2002a+
77+ Buhaug and Gates 2002+
78+ See Fearon and Laitin 2003; de Soysa 2002+
79+ Fearon forthcoming+
Natural Inﬂuences and Civil War 61
dence in these thirteen cases that rebel groups funded their startup costs by looting
natural resources or extorting money from resource ﬁrms+ Nor was there
evidence that grievances over insufﬁciently compensated land expropriation, environmental
degradation, inadequate job opportunities, or labor migration contributed
to the initiation of nonseparatist conﬂicts+ This does not imply that such
grievances are irrelevant; they may have contributed to the rise of low-level conﬂicts
and separatist conﬂicts+ But neither of these mechanisms explain the link
between natural resource wealth and the ten nonseparatist civil wars in this
sample+
The fourth ﬁnding is that in these thirteen cases, illicit drugs were not linked to
the onset of conﬂict+ In each of the four conﬂicts that occurred in major opiumand
coca-exporting states ~Afghanistan, Burma, Colombia, and Peru!, rebel movements
were uninvolved with the cultivation of or trade in drugs before the war
began+ In several cases ~Burma and Colombia!, the causal arrow ran in the opposite
direction: the civil war led to drug production by creating a fertile region that
fell outside the government’s control for a signiﬁcant number of consecutive growing
seasons, offering the rebels ideal drug-producing conditions+ In the other two
cases ~Afghanistan and Peru!, drug production and civil war seemed to be independently
associated with the weakness of the state’s jurisdiction in remote rural
areas, but neither one caused the other+ In all four cases, however, the production
of opium and coca—once it began—seemed to lengthen the conﬂicts by providing
funding to the rebels, or to both sides simultaneously+80
Fifth, resource wealth does not always make existing conﬂicts worse+ While the
net effect of resource wealth on conﬂict in this sample was harmful, the cases
suggest that resources sometimes have contradictory and even peace-enhancing
effects over the course of a civil war+ Resource wealth appeared to bring about a
quicker end to two wars+ Claims that resource wealth tends to heighten the intensity
of conﬂict may also be only partly correct+ Observers often note that combatants
ﬁght for the control of natural resources, and that these battles appear to
increase the war’s overall casualty rate+ But resources also lead to battleﬁeld cooperation
that may reduce the casualty rate+ In nine of the thirteen cases examined
here, combatants fought battles over resource wealth; in eight of these cases, combatants
also laid down their arms ~at other junctures! to cooperatively exploit these
same resources+
The sixth ﬁnding is that resource wealth and civil war are not linked by a single
mechanism, but a variety of mechanisms+ Moreover, these mechanisms can inﬂuence
a conﬂict’s onset, duration, and intensity+ No single mechanism appeared in
more than nine of the thirteen cases+ In twelve of the thirteen cases, resources had
more than one type of effect on conﬂict+ This multiplicity of causal linkages—and
the absence of a single, ubiquitous mechanism—may help account for the analytical
muddle, and contradictory ﬁndings, of earlier studies+
80+ On the different impacts of different natural resources, see Le Billon 2001; and Ross 2003b+
62 International Organization
Seventh, resources appear to play a different role in separatist conﬂicts than in
nonseparatist conﬂicts+ Grievances over the distribution of resource wealth helped
initiate two of the three separatist wars in the sample ~Sudan, Indonesia!, but grievances
of all types played no role in the ten nonseparatist wars, except for the ambiguous
case of Sierra Leone+ These two separatist conﬂicts were also the only
ones to face preemptive repression, which is a government’s use of terror to suppress
rebel movements that may interfere with resource exploitation+ This implies
that the geographical distribution of natural resources across a nation’s territory
may be important: if resource wealth is located in a region with separatist aspirations,
it may help precipitate a war and increase the war’s casualty rate+
Finally, the article describes four unforeseen mechanisms that link resource
wealth to subsequent conﬂict+ The ﬁrst is that resource wealth may increase the
danger that a foreign state will intervene on behalf of a nascent rebel movement;
in both the Sierra Leone and DRC II conﬂicts, these interventions triggered long
and costly civil wars+ The second and third mechanisms concern the sale of booty
futures—future exploitation rights to resources not under the seller’s control—
which may either initiate or prolong a conﬂict+ The sale of booty futures is a tool
of the weak against the strong: it can help provide aspiring rebel groups with the
funds they need to launch attacks on governments; it can also give governments
on the verge of defeat the ability to fund counterattacks+ In this sample it contributed
to the onset of at least two major wars ~Sierra Leone and the Congo Republic!
and the prolongation of three ~Angola, Sierra Leone, and the DRC II!+
The ﬁnal unanticipated mechanism is preemptive repression+ In two of the three
separatist conﬂicts in the sample ~Indonesia and Sudan!, the government took exceptionally
harsh measures against insurgencies, because they appeared to threaten
the government’s control of resource wealth+ These four mechanisms—along with
ﬁve of the seven mechanisms whose implications were tested in the sample—can
help account for the frequency, duration, and intensity of civil wars in resourcerich
states+
There are several ways that scholars might build on these ﬁndings to advance
the natural resources–civil war research agenda+ One way is by statistically testing
the hypotheses discussed here, using a complete civil war data set+ Thanks to
leading scholars, there are now several excellent databases on civil wars+81
At least
some of the hypotheses discussed in this article should be simple to test with existing
data sets—for example, hypothesis H10, which suggests that resource wealth
increases the likelihood of foreign intervention+ Hypotheses that are difﬁcult to
test with existing data sets—such as those concerning resource battles, cooperative
plunder, and booty futures—might be fruitfully explored with small-N studies
that assess their validity in a different ~and ideally, less-biased! sample of cases+
A second avenue of future research concerns the inﬂuence of gemstones and
narcotics on conﬂict+ Gems and drugs were causally linked to nine of the thirteen
81+ See Collier and Hoefﬂer 2002a; Sambanis 2001; Gleditsch et al+ 2002; Fearon and Laitin 2003+
Natural Inﬂuences and Civil War 63
conﬂicts in this study; yet these two resources are almost never included as explanatory
variables in large-N conﬂict studies+ There is, unfortunately, good reason
for this: data on the production of gemstones and illegal narcotics is scarce
and sometimes unreliable, because these items are often traded on the black market,
and it is difﬁcult to identify their countries of origin+ Better cross-national
data on gems and drugs would open the door to large-N testing and facilitate a
critical advance in knowledge+82
A third area for further study is how resources inﬂuence conﬂict intensity+ In
this thirteen-case sample, natural resources had an ambiguous effect on conﬂict
intensity: in nine cases, it appeared to heighten the casualty rate by causing combat
over resource wealth; but in eight of those nine cases, it may have reduced the
casualty rate at other junctures by fostering cooperation among the warring parties+
A large-N study on the determinants of conﬂict intensity, testing natural resources
as an explanatory factor, would help assess the net effect of resource wealth
on conﬂict+ Existing data sets have limited information about conﬂict intensity;
improved data could yield new insights on the role of resources+83
Finally, more work should be done to address the problems of endogeneity and
spuriousness+ While there is good evidence that natural resources inﬂuenced civil
war within this thirteen-case sample, it is still possible that the statistical correlation
between resources and conﬂict is caused by endogeneity or spuriousness+
Until these possibilities can be ruled out, a cloud of uncertainty will linger over
the claim that natural resources increase the hazard, duration, and intensity of civil
war+
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