A theory of competing interventions by external powers in intrastate conflicts: implications for war and armed peace

ABSTRACT

This paper presents a game-theoretic model of competing interventions in civil conflict. We analyze the conflict between an incumbent government (as defender) and its rebel group (as attacker) when the two parties receive military support from different external powers. In contrast to the traditional analysis of non-competing or biased intervention by a single third party, we first show how competition in external powers can strategically alter the outcome of the two-party conflict and then identify the conditions under which the defender launches an effective strategy to deter the attacker. We find that (i) when the stakes that the competing external powers have in their respective supported parties are equivalent, the amounts of military support endogenously offered by the external interveners are comparable. The government’s deterrence strategy is ineffective, and the fighting persists despite the warring parties’ valuations for political dominance being asymmetric. (ii) when the external power that supports the government has a higher stake than the competing external power that supports the rebel group, the government’s arming allocation can deter the rebellion. (iii) These results have implications for multi-power interventions so that the equilibrium outcome can be ‘armed peace’ or a prolonged war as observed in civil conflicts.

KEYWORDS:

• Competing interventions
• intrastate conflicts
• deterrence
• war
• armed peace

JEL CLASSIFICATION:

• D72
• D74
• H56

Acknowledgments

We thank David Peel, the Editor in Chief, and anonymous referees for insightful comments and suggestions, which lead to substantial improvements in the paper. Any remaining errors are, of course, ours.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Notes

¹ Intrastate or civil conflicts involve domestic interest groups competing for a political power to gain control over valuable resources. For studies, see, e.g. Gershenson and Grossman (2000), Azam and Mesnard (2003), Collier and Hoeffler (2004, 2009), Garfinkel and Skaperdas (2007), Vahabi (2010), and Chang, Sanders, and Walia (2015).

² Some third-party interventions have the objective of conflict management (i.e. United Nations peacekeeping missions). Such an ideal motivation may not drive all third-party actions. Regan (1998) links interventions by external powers to their national interests and considers it as the “paradigm of realism” and the dominant philosophy in international politics. For other studies on third-party interventions see, e.g. Morgenthau (1967), Bull (1984), Betts (1994), Blechman (1995), Regan (1996), Werner (2000), Cetinyan (2002), Siqueira (2003), Sanders and Walia (2014), Busch and Reinhardt (2006), Regan and Aydin (2006), Rowlands and Carment (2006), Balch-Lindsay, Enterline, and Joyce (2008), Chang and Sanders (2009), Amegashie (2010, 2014), Sanders and Walia (2014), Sawyer, Cunningham, and Reed (2015), Cunningham (2016), and Blouin (2018).

³ We use the term ‘peace’ to reflect an absence of fighting. If the government moves first by launching a successful preemptive strike against the rebel group, the latter is better off without allocating any consumable resource to fight. This approach follows the notion of ‘acquiescence’ in a sequential-move game between government and rebel as discussed in Grossman (1999), Gershenson and Grossman (2000), Gershenson (2002), Grossman and Kim (1995), and Chang et al., (2007a, 2007b).

⁴ For simplicity and without loss of generality, we assume that $V_1<2V_2$.

⁵ For alternative forms of contest success functions, see, e.g. Tullock (1980), Hirshleifer (1989), Skaperdas (1996), and Garfinkel and Skaperdas (2007).

⁶ When there is no external intervention such that $M=0$ the three-country, three-stage model reduces to a two-country, two-stage model as those examined in Gershenson and Grossman (2000), and Chang, Potter, and Sanders (2007b). Following Hillman and Riley (1989) and Gershenson and Grossman (2000), we consider asymmetric valuations associated with a contested prize which is political dominance in our analysis.

⁷ For studies that use a Stackelberg-type sequential-move game for primary parties in contest or conflict, see, e.g. Dixit (1987), Baik and Shogren (1992), Leininger (1993), Gershenson and Grossman (2000), Morgan (2003), Congleton, Hillman, and Konrad (2008), and Aanesen (2012).

⁸ This section is due entirely to an anonymous referee who suggests comparing the equilibrium outcome of competing interventions by two external powers to that of no outside intervention.