Tensions between Iran and the United States are escalating again in Syria following a drone attack on a Coalition base in northeast Syria and subsequent tit-for-tat attacks. In a statement released yesterday, the Pentagon claimed a drone of Iranian origin struck the base near Hasakah, Syria, killing one U.S. contractor and wounding five U.S. service members and an additional U.S. contractor. In response, the United States conducted airstrikes in eastern Syria against facilities used by “groups affiliated with Iran’s Islamic Revolutionary Guard Corps (IRGC),” Defense Secretary Lloyd J. Austin III stated.

Today, a new missile strike targeted a U.S. base in the same region, just hours after Secretary Austin’s announcement. 

Hundreds of U.S. troops remain stationed in Syria to ensure the continued defeat of ISIS. (A U.S. base in Al-Tanf, southeast Syria, has less clear objectives.) These troops have repeatedly clashed with Iranian-backed groups since 2017. In the past two years alone, Iranian-backed groups have conducted drone or rocket attacks against U.S. troops in Iraq and Syria at least 78 times – a sustained increase since the Trump administration killed IRGC Qods Force Commander Qassem Soleimani in a drone strike in January 2020. 

The Biden administration has not yet publicly articulated the legal basis for the latest strike. Based on past precedent, the administration is likely to claim these strikes were carried out under the President’s unilateral Article II authority, rather than the 2001 Authorization for Use of Military Force (AUMF). Under the War Powers Resolution, the administration should submit a report to Congress within 48 hours of the strike outlining the basis for the use of force. Previously, the United States has claimed similar strikes were necessary to “deter” future attacks – a justification that has begun to ring hollow after repeated cycles of hostilities and one which has a controversial claim to legality under international law (see competing views at Just Security put forward by Adil Haque and by Ryan Goodman). 

Notably, Congress has not expressly authorized military operations against Iranian-backed militia groups in Syria (though some might claim the 2001 AUMF applies). Coincidentally, on Wednesday, lawmakers resoundingly voted against Sen. Lindsay Graham’s proposal to amend the 2002 AUMF by repurposing it to authorize military force against “Iranian-backed militias operating in Iraq” (Yea-Nay Votes: 36-60), suggesting there may be little support for broadening authorities to Syria. 

For further analysis on this topic, see: “Tit-for-Tat Hostilities in Syria: War Powers and International Law Applications” by Tess Bridgeman and Brian Finucane, and “Still at War: the United States in Syria” by Tess Bridgeman and Brianna Rosen.

Image: A simulation of a drone strike (via GettyImages).