The size of the costs the coercer incurs depends on the strength of the target’s domestic opposition. The more severe the targeted leader’s domestic threat, the more resolved the leader will be to resist, and the larger the threat the coercer must make to convince the leader to back down. This means that the greater the leader’s domestic threat, the greater the foreign power’s mobilization must be, the larger the international coalition it must build, and/or the more bombs it must drop to overwhelm the target’s incentive to resist.37 In extreme cases, the foreign power may even have to achieve a military victory before a leader with a strong domestic incentive to resist agrees to a settlement.38 To be sure, foreign powers may encounter some of the same costs when carrying out regime change. However, as I will explain later, the key difference between expected coercion and regime change costs is that, as the opposition’s strength grows, the former will rise, while the latter will fall. All told, foreign powers may have to incur a variety of high costs to convince targeted leaders to accept politically risky settlements, and these costs could exceed the expected costs of regime change.
THE COSTS OF ENFORCEMENT
The long-term costs of enforcing a settlement can also inflate the cost of a bargaining agreement. As long as targeted leaders face domestic opposition that makes their compliance with a deal politically costly, they will be tempted to renege on their commitments as soon as the foreign power’s pressure diminishes. In the rationalist literature, actors who have an incentive to cheat on a settlement face what is known as a commitment problem. The stronger state anticipates the targeted leader will cheat once the opportunity arises and so rejects the possibility of bargaining and resorts to war. In some cases, the threat of renewed hostilities may deter the target from reneging. But if the target state doubts the stronger side’s willingness to enforce the settlement or if it acquires greater military capacity, it may attempt to renege. After World War I, for example, Germany challenged the Treaty of Versailles once it became apparent the victors were reluctant to enforce it. Similarly, Joseph Stalin authorized North Korea’s invasion of South Korea in 1950, believing that the Truman administration would not interfere.39
To assure compliance, the stronger state must convince the lesser power’s leaders that cheating would be detected and punished. To do this, it can use international observers to monitor compliance or it can take more invasive (and potentially more effective) measures, such as demanding partial policy control or stationing troops on the target state’s soil. France and Belgium, for example, occupied the German Ruhr region from 1923 to 1925 to enforce the reparation terms imposed on Germany after World War I. Less than two decades later, Nazi Germany enforced its armistice with Vichy France by occupying northern France. Other enforcement measures include peacekeeping missions, which are frequently deployed to monitor cease-fire agreements.
Much like coercion, enforcement measures can entail a variety of costs, ranging from monetary and military ones to domestic political and reputational costs. For example, the French and Belgian troops in the Ruhr encountered a campaign of passive resistance, which forced the French to increase their occupation force from 80,000 to 140,000.40 Fears of casualties and their attendant domestic political costs led US policymakers to push for the downsizing of the small United Nations (UN) peacekeeping mission in Rwanda during the 1994 genocide in that country.41 Enforcement measures must also be maintained as long as the target retains an incentive to renege. Over time, these costs add up. Peacekeeping missions in such places as Cyprus (1964), the Sinai (1981), and Kosovo (1999) are still in operation today, though the conflicts that generated them have long since ended.
The potentially high cost of indefinitely enforcing a settlement explains why the stronger state sometimes refuses the resignations of targeted leaders. If complying with a settlement will be just as politically costly for the targeted leader’s chosen successor as it was for the leader, then that successor will have the same incentive to renege. Unless the more powerful state installs a new leader who is reliant on a different set of supporters and/or political institutions, then it may find itself stuck paying high enforcement costs. This is why Soviet leader Brezhnev ignored Dubček’s offers to resign as first secretary of the Communist Party of Czechoslovakia in their phone call one week before the Warsaw Pact invasion. Letting Dubček resign would have left reformers in charge. Brezhnev hoped that an invasion would instead prompt Czechs aligned with Moscow to seize power and overturn the reforms of the Prague Spring.42
The costs of forcing a leader to accept and to abide by a settlement may tempt the more powerful state to pursue FIRC as a cheaper alternative, especially when domestic opposition drives the targeted leader’s refusal to concede. As I will explain, while the target’s domestic opposition can make a settlement appear costly to attain, that opposition can also make the leader appear cheaper to depose. As long as the opposition is marginally more willing to make concessions than the leader, then the stronger power may conclude that it can attain its policy aims at a lower cost by partnering with the opposition to overthrow the leader.
The Costs of Imposing Regime Change
Some of the costs of coercing a target to accept and abide by an agreement are the same as those associated with regime change. The financial, political, and diplomatic costs of launching an invasion to coerce the leader will also be borne if an invasion is required to depose the leader. The long-term costs of enforcing an agreement could also be matched by the long-term costs of propping up a puppet. But there is an important difference between the costs of bargaining with a leader and the costs of overthrowing a leader. Whereas strong domestic opposition increases a foreign power’s costs of obtaining an enforceable agreement, strong domestic opposition will decrease the expected costs of regime change. This is because politically weak leaders are not just more resolved to resist; they are also often easier to overthrow. As long as the stronger state can find an opposition group willing to collaborate, the more powerful that group, the more it can assist the foreign power in toppling the leader, thereby reducing the costs of regime change to the foreign power. This opposition need not be the same as the one causing the leader’s resistance. A leader, for example, might refuse the foreign power’s demands in order to defend against an internal rival, while the foreign power uses external opposition to impose regime change.
In what follows, I first address how domestic opposition, whether internal or external, affects the foreign power’s estimates of regime-change costs and why foreign powers can often find opposition groups willing to collaborate. I end with a discussion of how major events or crises can serve as catalysts for regime change by prompting policymakers to reassess the costs of using military force.
THE STRENGTH OF THE DOMESTIC OPPOSITION
A domestic opposition’s power depends primarily on two attributes—the extent of its military capabilities and the size and unity of its political following. Opposition groups with military capabilities can lower the costs of removing their nation’s leader in a variety of ways. First, they can conduct military operations and absorb casualties, thus reducing the number of troops that the foreign power must contribute to a military invasion. In 1852, Brazil looked to partner with local actors to overthrow Argentinean dictator Juan Manuel de Rosas. Knowing it could not overthrow Rosas on its own, Brazil instead aligned with the politically ambitious Argentinean governor of Entre Ríos, Justo José de Urquiza. It was Urquiza’s army of twenty thousand, assisted by a much smaller number of Brazilians and Uruguayans, that ultimately defeated Rosas.43 Even when relatively small in number, opposition fighters can still contribute militarily to a foreign power’s invasion by conducting sabotage operations, providing intelligence, harassing enemy troops, and generating propaganda to hasten a military victory. Both Nazi Germany and the Soviet Union built their informal empires by relying on pro-Nazi and pro-Soviet domestic opposition groups that served as a fifth column.44
Opposition groups that represent a former ruling faction often have a ready-made group of supporters willing to fight for them. During the nineteenth and early twentieth centuries, liberal and conservative regimes in Central America intervened repeatedly in neighboring states to restore their ideological allies to power.45 Between 1855 and 1907,