Somewhat surprisingly, given isolationist campaign rhetoric, the Trump administration finds itself being asked to define its legal approach to use of force. For the first few months of the Trump administration, its Syria strategy was focused on the fight with ISIS. Despite ever-mounting civilian casualties, President Trump seemed content to leave President Assad in place. When Syria used sarin gas—a particularly toxic chemical weapon—on its own civilians, however, President Trump claimed that the attack changed his “attitude toward Syria and Assad very much.” He condemned the attack, and, after U.S.-led efforts for U.N. action failed, President Trump authorized a missile strike on the Syrian air base that launched the chemical attacks.
Is such a strike lawful? Under traditional understandings, states may not engage in the use of force under the U.N. charter unless they have a case for self-defense or a U.N. authorization. Some have argued that states additionally ought to be able to use force for humanitarian interventions, even in the absence of textual permission under the U.N. charter.
President Trump and his administration have offered several short policy justifications for the strike, but the legal grounding is still unclear. Trump stated the very night of the attack that preventing and deterring chemical weapons was in the “vital national security interest” and that the region’s continued destabilization “threat[ened] the U.S. and its allies.” Secretary of State Rex Tillerson expanded on this ground, suggesting that Syrians might bring these chemical weapons “to our shore [which] is a direct threat to the American people.” Yet, multiple administration statements also suggest the strike was deeply humanitarian in nature, responding to, and attempting to prevent future, Syrian civilian casualties. For instance, National Security Advisor H.R. McMasters stated that the attack was motivated by the “risk of this continued, egregious inhumane attacks on innocent civilians with chemical weapons.” Yet, none of these statements go so far as to explain why the attack is either consistent with existing international law governing the use of force or is part of a new strategy to broaden legal authority for force in service of humanitarian interventions or enforcement of rules on means and methods.
This opacity as to the legal justification is consistent with President Trump’s disinterest in legal micromanagement of conflict.1 Rather than explain whether the U.S. is invoking an expansive understanding of self-defense or using this as a moment to craft a new standard for humanitarian interventions, President Trump has allowed his underlings to craft ad hoc, and often competing, understandings of the reasons for the use of force. For instance, the use of incendiary weapons, such as barrel bombs, against civilians might be a sufficient reason for additional strikes, but, then again, maybe not. This leaves the international community and domestic public uncertain as to when Trump would find further strikes in Syria, or elsewhere, justified. Relatedly, does the Trump administration view a policy justification as per se including a legal justification, or is the Trump administration suggesting that any justification is enough, even if it is not technically legal?
Similarly, this legal muddiness about the Syria strike also makes it difficult to assess whether the administration is walking back the America First doctrine here. One might fairly view the strike as outside America’s direct interests. Perhaps the gruesome photographs of Syrian victims generated a new sympathy for civilian casualties, motivating the strikes and the future use of force to achieve regime change. Yet, one might equally view the strike as a one-off designed to keep the norm against chemical weapons in place so that future U.S. soldiers will not be at risk or so states know that we enforce our agreements. In service of this view, it is worth noting that President Trump has not lifted the ban on Syrian refugees nor was he motivated to act by any of the other laws-of-war violations perpetuated against Syrian civilians. While the direct-national-interest argument for the strikes is tenuous, it may still be the primary motivation. Like with the laws of war, the first 100 days leave us with more questions than answers, but we do have one very high-profile data point in the Syria strike from which we can try to discern an emerging doctrine.
* Professor of Law, University of Illinois College of Law, Urbana-Champaign. She has written extensively on the intersection of the laws of war, civilian casualties, and civil society.
1 On the domestic-law side of things, unlike his predecessor, Trump did not seek, or attempt to build, congressional approval for the strikes nor did he engage in extended consultative processes before acting. But, he did have significant conversations with the defense secretary, secretary of state, and the national security advisor.