War as an Enforcement Problem

Interstate Conflict over Rebel Support in Civil Wars

Kenneth SchultzStanford University

Observations

1. Civil wars are associated with a high probability of militarized interstate disputes (Gelditsch, Salehyan, and Schultz 2007)

2. The presence of external rebel bases is associated with a high probability of interstate militarized disputes (Salehyan 2007)

3. Conflict between states and neighbors that host/support rebel groups often involve repeated attacks over a protracted period of time.

Rationalist Explanations of War

1. Information asymmetries and incentives to misrepresent

2. Indivisibility

3. Commitment problems• exogenous power shifts• endogenous power shifts• first-strike advantage• unilateral reneging on policy concessions

Basic Model• Two states, A and B, in a potentially infinite

game.• State A has control over a policy that benefits

it and harms state B.• There is some delay or imperfection in B’s

ability to detect the policy level set by A in each period.

• State B can use military force which– inflicts costs on both sides– has some probability of leading to an imposed

solution

State B

State A State A

Nature

p1 – p

The Enforcement Game

A

B

c

c

1

A

B

x c

x c

1

x

x

Attack Not Attack

Move on to next period

x x

A Cooperative EquilibriumDoes there exist some bargain , such that1. State B plays Not Attack in every period t as

long as state A has never played x > in any previous period. If state A plays x > in any period, then state B plays Attack in all subsequent periods.

2. In every period, state A plays x = if state B has always played according to (1) and x=1 if state B has ever deviated from (1).

Solution

• For any deal , the present discounted values of cooperation are

• Define “war” as a sequence of periods in which the states play {Attack, x=1} until B wins.

• War is inefficient. There always exists some such that

rA > wA

rB > wB

1,

1 1A Br r

Solution

• But for the deal to be enforceable, it must be the case that

• These conditions place bounds on the enforceable deals:

• A deal exists if and only if

1A A

B B

r w

r w

and

Solution

1. If p ≤ cB then B is never willing to attack, so a peaceful deal always exists at x = 1.

2. If cA + cB > p > cB then an enforceable deal exists if the discount factor () is sufficiently large.

3. If p > cA + cB, then no enforceable deal exists.

The Bargaining Range as a Function of the Discount Factor

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Lower bound

Upper bound

Upper bound

Lower bound

Possible bargains

0.4, 0.5, 0.2A Bp c c 0.4, 0.1, 0.2A Bp c c

Policy as an Instrument: A Revised Game

1. State B determines • distribution of good,• decides to Attack or Not Attack

2. In the event of attack, Nature determines outcome: B wins with probability p

3. State A sets level of policy,

4. Nature determines outcome of A’s policy: A wins with probability s

[0,1]x

[0, ]s s

A Cooperative Equilibrium

Does there exist some bargain (, ), such that1. State B plays {Not Attack, x = } in all

periods t as long as state A has played s ≤ in all previous periods. If state A plays s > in any period, then state B plays {Attack, x = 0} in all subsequent periods.

2. In every period, state A plays s = if state B has always played according to (1) and s = s if state B has ever deviated.

An Example of Incompatible Bargaining Demands in the Revised Game

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 0.05 0.1 0.15 0.2 0.25 0.3

Lower bound

Upper bound

Empirical Application

Hypothesis 1: – Controlling for the overall level of conflict within

the dyad, the states are more likely to experience militarized conflict during periods of rebel support than during periods without rebel support.

– Dyads experiencing rebel support experience a higher level of militarized conflict than dyads with territorial disputes.

Hypothesis 2: Any given state B is more likely to initiate military conflict against any state A when state A is supporting rebels in B than when state A is not supporting rebels, holding constant the overall rate of conflict initiations by B against A.

Empirical Application

• Hypothesis 3: Agreements to curb rebel support are more effective at reducing interstate violence if they make provision for monitoring by third parties than if they do not.

• Hypothesis 4: Agreements to curb rebel support are more effective at reducing interstate violence if they are coupled with substantive concessions (e.g., power sharing, regime change, territory) by the targeted state than if they are not.

Data Sources

• International conflict: Militarized interstate disputes (MIDs)

• Civil conflict: Uppsala Armed Conflict Database

• Rebel support: Non-State Actors in Civil Wars (Cunningham, Gleditsch, and Salehyan)

• Agreements: Self collected

Rebel Support and MIDs

Rebel support

No rebel support

MID Onset288

(26.2%)

1,284

(2.3%)

No MID813

(73.8%)

54,376

(97. 7%)

2=2300

Variable Probit Probit w/time Conditional logit

Civil conflict 0.174 0.137 0.191

Z (0.057)** (0.046)** (0.103)

Rebel support 0.830 0.542 1.001

Z (0.099)** (0.078)** (0.161)**

Reciprocal support -0.047 -0.178 0.527

Z (0.181) (0.146) (0.413)

Territorial dispute 0.701 0.447 0.761

Z (0.092)** (0.067)** (0.188)**

Democratic dyad -0.480 -0.377 -0.155

Z (0.090)** (0.067)** (0.204)

Contiguous 0.783 0.577 0.436

Z (0.085)** (0.065)** (0.705)

Colonial Contiguity 0.374 0.314 1.631

Z (0.091)** (0.067)** (0.249)**

Ln(Capability ratio) -0.105 -0.100 -0.396

Z (0.018)** (0.013)** (0.095)**

Alliance similarity -0.701 -0.529 -1.050

Z (0.116)** (0.082)** (0.278)**

Constant -1.768 -0.846 Z

Z (0.104)** (0.105)** Z

Observations 39789 39789 11344

Comparing Rebel Support to Territorial Disputes

0.0910.12

0.37

0.26

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Baseline Civil conflict Civil conflictw/rebel support

Territorialdispute

Pre

dict

ed P

r(M

ID)

Rebel Support and MID Initiations

No Rebel support

Initiator supports

Target supports

Both support

MID Initiation

1,100

(1.0%)

106

(12.6%)

119

(13.9%)

24

(16.8%)

No MID Initiation

106,959

(99.0%)

735

(87.4%)

735

(86.1)

119

(83.2%)

2=2300

Variable Conditional Logit

Civil conflict in initiator 0.463

Z (0.099)**

Civil conflict in target 0.314

Z (0.103)**

Initiator supporting rebels 0.593

Z (0.181)**

Target supporting rebels 0.730

Z (0.170)**

Initiator democratic 0.197

Z (0.155)

Target democratic 0.324

Z (0.147)*

Both democratic -0.626

Z (0.212)**

Contiguous 1.169

Z (0.552)*

Colonial contiguity 1.839

Z (0.240)**

Initiator’s share of capabilities 0.442

Z (0.601)

Alliance similarity -0.370

Z (0.218)

Observations 17509

Agreement Data

• Population: Pairs of states in which at least one was supporting rebels against the other, 1946-2001.

• Key provisions:– not to harbor or support groups engaged in hostilities

against the other state,– not to permit its territory to be used for planning or

launching attacks on the other state,– to prevent and/or not participate in acts of subversion

against the other state,– to engage in joint military operations against groups

engaged in subversion,– not to interfere in the internal affairs of the other state.

The Effect of Agreements

Variable (1) (2) (3)

Civil conflict ongoing 1.233 1.207 1.191

Z (0.218)** (0.219)** (0.220)**

Shared democracy -0.683 -0.625 -0.609

Z (0.438) (0.440) (0.441)

Post agreement -1.063 -0.381 -0.206

Z (0.247)** (0.338) (0.357)

Post agreement with concessions z -1.331 -0.897

Z Z (0.471)** (0.543)†

Post agreement with third party Z z -0.912

Z Z Z (0.552)†

Observations 1994 1994 1994

2 69.97** 78.19** 80.95**

† significant at 10% * significant at 5%; ** significant at 1%

“The problem in the ‘just talk to Iran’ or ‘just talk to Syria’ idea is that, if Iran and/or Syria believe that it is in their interests to have a stable Iraq, then they will act in accordance with that. If they don’t believe that it is in their interest, they will not, or they will try to exact a price.”

—Condoleezza Rice,

Dec. 21 2006, News Hour