1. War as an Enforcement Problem Interstate Conflict over Rebel Support in Civil Wars Kenneth Schultz Stanford University

2. 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.

3. 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

4. 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

5. State B State A Nature p 1 – p The Enforcement Game Attack Not Attack Move on to next period x x

6. A Cooperative Equilibrium Does there exist some bargain , such that 1.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).

7. 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 r A > w A r B > w B

8. 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

9. Solution 1.If p ≤ c B then B is never willing to attack, so a peaceful deal always exists at x = 1. 2.If c A + c B > p > c B then an enforceable deal exists if the discount factor (  ) is sufficiently large. 3.If p > c A + c B, then no enforceable deal exists.

10. The Bargaining Range as a Function of the Discount Factor Lower bound Upper bound Lower bound Possible bargains

11. 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

12. A Cooperative Equilibrium Does there exist some bargain ( ,  ), such that 1.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.

13. An Example of Incompatible Bargaining Demands in the Revised Game Lower bound Upper bound

14. 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.

15. 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.

16. 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

17. Rebel Support and MIDs Rebel support No rebel support MID Onset 288 (26.2%) 1,284 (2.3%) No MID 813 (73.8%) 54,376 (97. 7%)  2 =2300

18. VariableProbitProbit w/timeConditional logit Civil conflict0.1740.1370.191 Z(0.057)**(0.046)**(0.103) Rebel support0.8300.5421.001 Z(0.099)**(0.078)**(0.161)** Reciprocal support-0.047-0.1780.527 Z(0.181)(0.146)(0.413) Territorial dispute0.7010.4470.761 Z(0.092)**(0.067)**(0.188)** Democratic dyad-0.480-0.377-0.155 Z(0.090)**(0.067)**(0.204) Contiguous0.7830.5770.436 Z(0.085)**(0.065)**(0.705) Colonial Contiguity0.3740.3141.631 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-1.768-0.846Z Z(0.104)**(0.105)**Z Observations39789 11344

19. Comparing Rebel Support to Territorial Disputes

20. 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

21. VariableConditional Logit Civil conflict in initiator0.463 Z(0.099)** Civil conflict in target0.314 Z(0.103)** Initiator supporting rebels0.593 Z(0.181)** Target supporting rebels0.730 Z(0.170)** Initiator democratic0.197 Z(0.155) Target democratic0.324 Z(0.147)* Both democratic-0.626 Z(0.212)** Contiguous1.169 Z(0.552)* Colonial contiguity1.839 Z(0.240)** Initiator’s share of capabilities0.442 Z(0.601) Alliance similarity-0.370 Z(0.218) Observations17509

22. 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.

23. The Effect of Agreements Variable(1)(2)(3) Civil conflict ongoing1.2331.2071.191 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 concessionsz-1.331-0.897 ZZ(0.471)**(0.543)† Post agreement with third partyZz-0.912 ZZZ(0.552)† Observations1994 22 69.97**78.19**80.95** † significant at 10% * significant at 5%; ** significant at 1%

24. “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