Now that the dust from the U.S.–U.K.–French operation against Syria has settled, I want to follow up on something I said when news of it first broke. Like most commentators, I argued that the operation did not satisfy the formal legal doctrine on the use of force. By this I meant that it was inconsistent with the…

The United States, Britain, and France have attacked various chemical weapons facilities in Syria. Even before they acted, a number of commentators claimed that any such attack would be internationally unlawful. Below, I explain why that claim is too simplistic and how we should situate the operation in the jus ad bellum going forward.

Note from the Editors:  This week we hold the first EJIL:Talk! Contributing Editors' Debate, where some or all of our distinguished Contributing Editors lend their views on broad themes of international law and the state of the art, science, and discipline of international law.  Our thanks to Andreas Zimmermann (Co-Director of the Berlin-Potsdam Research Group, 'The…