"This article, first published as an ASIL Insight, is reprinted with permission from the American Society of International Law, www.asil.org.”
On May 2, 2011, U.S. forces entered Pakistan—without the Pakistani government’s consent—to capture or kill Osama Bin Laden. In the wake of the successful U.S. military operation, the Pakistan Government objected to the “unauthorized unilateral action” by the United States and cautioned that the event “shall not serve as a future precedent for any state.” Former President Musharraf complained that the operation violated Pakistan’s sovereignty. The episode implicates a host of important legal and political issues. This Insight focuses on one of them: when may one state use force in another state’s territory in self-defense against members of a non-state armed group, and what constraint does the principle of sovereignty impose on that action?