International Law’s Irrelevance to President Trump’s ‘Winning in Afghanistan’ Strategy

President Trump’s remarks on his administration’s “winning in Afghanistan” strategy were thin on details. In particular, Trump said little to resolve the nearly 16-year debate about the United States’ proper goals in Afghanistan. As the New York Times suggested a few days ago, Trump’s failure to specify such goals concretely enables him to “[shield] himself against potential backlash from his political base and from the American public, which has grown weary of the war.”

One serious problem here is that public scrutiny is the only check on the president’s strategy. Anyone hoping that law, and specifically international law, could offer some independent guidance for or limits on the U.S. strategy in Afghanistan, should know: It does not.

As I explain in a newly published article, war used to be a lucrative business that allowed states to articulate numerous self-serving goals and to pursue them by force. War was a legitimate instrument of territorial expansion, religious conversion, debt collection, dispute resolution and punishment for injury. States could go to war to seek and achieve all these goals, and the war did not have to end before these goals were achieved. This was true not only as a matter of raison d’etat but also sanctioned by the ethical prescriptions of the time under Just War Theory.

With the modern development of jus ad bellum—the international law governing the use of force—states’ rights to wage wars were significantly constricted. The 1945 U.N. Charter, building on the 1928 Kellogg-Briand Pact, prohibited the use of force by states for any cause or goal other than self-defense. It was an undoubtedly progressive development that limited war as an instrument of statecraft. Yet the modern jus ad bellum has nonetheless made the goals of war harder to define and the end of war harder to determine.

As the law made self-defense the only legitimate justification for waging war, every goal of war must be articulated in terms of self-defense, and the goals of self-defense, in turn, expand endlessly. They can include, for example, installing a democratic government, improving child literacy, empowering girls and women through education, enhancing agricultural production, building advanced infrastructure, securing economic stability, or eliminating all terrorist threats. Over the past 16 years, U.S. officials and nongovernmental experts offered all of these values at one point or another as metrics of success in Afghanistan. These goals were all cited to promote the legitimate self-defense interests of the United States and to answer the question, “Are we safe again?”

The question of whether the invasion of Afghanistan in October 2001 was justified as an exercise of self-defense under the terms of the U.N. Charter has been debated by legal scholars. But the question of what goals actually promote self-defense remains largely underanalyzed. This, I believe, is not so much for lack of attention but because international law offers little specific guidance on what and how much count as a legitimate security interest. International law sets certain limits on the initiation of war but far fewer on ending war.

As a result, we can have no consensual vision of what victory should look like and of what self-defense demands or justifies. In a world of perpetual threats, security is never fully satisfied. Today’s legal framework tolerates, and indeed invites, perpetual war.

With international law’s too-broad mandate to perpetuate war, the responsibility falls back to politics to demand and debate a clear statement of the administration’s goals in Afghanistan and foster debate over how to achieve those ends. Ultimately, such an articulation of goals—beyond the initial justification to use force—should also become part of the international legal requirements for legitimately employing force in self-defense.