In this post, I want to evaluate the link between two contemporary foreign policy issues that are generally viewed as unrelated. The first is ongoing U.S. military assistance to Syrian rebels. As Reuters reported last week, the United States is currently supplying a variety of small arms, anti-tank rockets, and other items to “moderate” rebel factions, and Congress has approved funding for future deliveries through the end of the fiscal year. The second issue is the Obama Administration’s decision to sign the Arms Trade Treaty (“ATT”) last September. While it’s far from clear that the United States will ratify the ATT, an established doctrine of international law holds that the act of signature triggers an interim obligation to refrain from conduct that would defeat the treaty’s “object and purpose.” This obligation might restrict the ability of the United States to supply arms to the rebels, and raises questions about the legality of the ongoing transfers. To understand why, it’s necessary to consider the text of the ATT, the rebels’ conduct, and the nature of the interim obligation.