Hot pursuit in Syria and in history

Pancho Villa (Smithsonian)
Secretary of State John Kerry justified the use of U.S. airpower in Syria in part on the shaky legal grounds of “hot pursuit.” Presumably this would entail the use of force to pursue militants who committed some crime in Territory X but fled into Territory Z and would allow X to temporarily violate Z’s sovereignty. The phrase has a long and storied history. In the 20^th century, the idea of chasing bandits across borders conjures an image of Pancho Villa and the United States’ failed raid into Mexico to nab him — as anyone familiar with the Townes Van Zandt tune “Pancho and Lefty” will appreciate.
But the use of the phrase raises several normative and legal questions when applied to Syria, and a look at the empirical track record may shed light on them. First, the extremist group known as the Islamic State has not directly attacked us. Killing American journalists on camera is a horrific act but not a legitimate casus belli. Presumably we would be acting on Iraq’s behalf. U.N. Ambassador Samantha Power, for example, cited the United States’ “inherent right of individual and collective self-defense.” There is some slippage here in which U.S. officials appear to use “self defense” and “hot pursuit” interchangeably.
Take Kerry’s recent testimony: “Iraq is asking us to help them … and as a matter of right, if they’re being attacked from outside their country, you have a right of hot pursuit. You have a right to be able to attack those people who are attacking you as a matter of self-defense.” He is correct, but only up to a point. First, the two concepts are not interchangeable. Self-defense is well grounded in international law under Article 51, though it requires first that an attack take place to defend oneself against. Hot pursuit, on the other hand, is still in dispute, as it stems from an obscure law of the seas allowing ships to pursue other ships on the high seas but requires a chase be underway — as the Pancho Villa case highlights. So presumably we would be allowed to chase Islamic State militants fleeing into Syria, but not sedentary Islamic State militants holed up in the city of Raqqah. Neither legal justification constitutes a blank check to violate a neighbors’ sovereignty willy-nilly. And both require that states use force that is proportionate, immediate, necessary and a means of last resort.
These legal criteria come out of a 19th-century ruling from the Caroline case. A more recent case — the ICJ ruling against the United States in the 1986 Nicaragua case — is also applicable. The court ruled that interventions by the United States, which famously supported the Contras to unseat the Sandinista government, did not “in itself amount to a use of force,” yet nor was the Nicaraguan government liable for its failure to halt arms flows into insurgents’ hands in El Salvador. The operative phrase here, as it pertains to an intervention against Syria, is “effective control” — since one could argue that Syrian President Bashar al-Assad neither controls the actions of the islamic State nor is capable of preventing their activity. As Power put it, “The Syrian regime has shown that it cannot and will not confront these safe havens effectively itself.” But here again, the rationale for our use of force rests on the ineffectiveness of Assad, not on the atrocities — or imminent threat posed — by the Islamic State (or by the group known as Khorasan).
Regardless of the phrase’s legality, what can we learn from how “hot pursuit” has been applied by states in the past? Looking at the limited data available on such raids, namely from the Correlates of War MIDs and International Militarized Intervention (IMI) datasets, a few interesting, if unclear, patterns emerge:
First, in many cases of cross-border incursions, the states doing the pursuing and hosting do a switcheroo. For years, Iraq used to chase Kurdish militants into Turkey. Then in the 1990s, Turkey began chasing Kurdish militants into Iraq. Ditto Venezuela pursuing Colombian poppy farmers into Colombia in 1995 (later, Colombia would violate Venezuelan and Ecuadoran borders in pursuit of FARC rebels). The mechanism behind this is unclear, but it may be that some kind of accommodation is made between the chasing state and the rebel group, thus allowing de facto sanctuary, which then provokes the neighboring state to pursue. Another plausible mechanism is state capacity — as states extend their writ and means of coercion, rebels are pushed beyond their borders.
Second, during the Cold War, pursuing states were often proxies acting with the external blessing of a great power, which perhaps gave them a feeling of legal immunity to violate sovereign borders with impunity. A case in point is Nicaragua pursuing guerrillas into Costa Rica in 1978, or the too-many-to-count interventions against Mozambique and Angola. Cross-border raids were not limited to third-world proxies, of course: The U.S. Army did a fair amount of pursuing Viet Cong guerrillas in Cambodia. Moreover, a surprising number of the recorded hot-pursuit raids during this era were the results of accidental crossings and military mishaps that often resulted in apologies by the pursuing state. (That rarely happens anymore.)
Third, the relationship between hot-pursuit raids and civil wars is not straightforward. Of course, there are almost always spillover effects of internal fighting. For example, Pancho Villa’s raid occurred in the midst of the Mexican revolution. The Congo saw maybe the most hot-pursuit raids in history. And more recently, Turkey’s civil war against Kurdish rebels corresponded with a wave of “hot-pursuit” raids into Iraq. Yet, one might also expect civil wars to be negatively correlated with such raids, on the logic that rebels in weak or war-torn states should see less need to cross borders. That is not always the case, to be sure. Even in low-capacity states, when militaries begin to use more lethal force, we see rebels flee. Boko Haram militants, for example, fled into Cameroon recently, prompting a border raid by the Nigerian military.
Finally, empirically, hot-pursuit raids tend to occur between neighboring states hostile to one another. Burma’s pursuit of Karen rebels in Thailand, Iran’s pursuit of Kurdish rebels in Iraq and Colombia’s pursuit of FARC militants in Ecuador provide cases in point. Yet in the current debate over CT strikes against the Islamic State in Syria, we run into the fact that Iraq and Syria are nominal allies, not enemies, thus inviting the prospect of Syria carrying out cross-border strikes against the Islamic State in Iraq and vice versa (in addition to U.S. airstrikes). We might think of such raids as a kind of “gateway drug” for states itching to go to war. Consider Israel and its Arab neighbors in the 1960s and 1970s, or Russia’s 2002-2003 raids into Georgia’s Pankisi Gorge. But in more recent times, such raids appear to act more as a substitute for interstate war, not as a harbinger of one. After all, the current rate of cross-border raids is consistent with their Cold War-era highs, and yet we see fewer interstate war onsets, suggesting either a lack of conflict escalation, a substitution effect or a normative acceptance of targeted raids. Moreover, these raids are just as likely to follow conflict as to presage it, as Iran’s incursions into northern Iraq in the 1990s and Rwanda’s post-genocide pursuit of Hutu militias in Congo suggest.
So what does this mean for our ability to intervene in Syria? Isn’t Kerry’s use of the phrase just confirmation of the might-makes-right truism of international politics? Not entirely. After all, the United States has until recent weeks avoided violating Syrian sovereignty, despite no shortage of opportunities (and threats) to use force. Clearly, the administration wants to be on firm legal ground before bombing, say, Raqqah. Second, we’ve seen this movie before: During the Iraq war, according to documents released by WikiLeaks, the U.S. military was authorized to pursue insurgents into Iran and Syria but never did (over the heckling of some neoconservatives to do so). In other words, the United States has no problem with dropping drones in places like Pakistan or Yemen — presumably under the legal justification of UNSC Resolution 1373 or the Authorization for Use of Military Force (AUMF)  — but when it comes to “hot pursuit,” it generally shies away from the practice. Finally, the real question comes when the the Islamic States foreign fighters scramble in the wake of our intervention and fan out across the region. Would “hot pursuit,” much less the AUMF, allow us to chase them into Turkey, Lebanon, Jordan — or, gasp, all over Europe?
Nor does the Bush-era logic of using preventive force in anticipation of gathering threats, whether from state leaders (Saddam Hussein) or nonstate actors (the Islamic State) hold much legal precedent. Yet the Obama administration appears to be invoking anticipatory self-defense, on the grounds that the islamic States (or Khorasan) has intent to strike the U.S. homeland or kill more Americans.
The legacy of hot-pursuit raids is a mixed one, and one tangled in legal uncertainties. The Obama administration is right to finally intervene in Syria, but its justification feels a tad flimsy and unpersuasive.