摘要:In the years since the 1999 North Atlantic Treaty Organization airstrikes on Serbia to prevent ethnic cleansing of the Kosovar Albanians, international law has been moving in fits and starts toward recognition of a limited right of humanitarian intervention in the absence of United Nations Security Council approval. But all the ingredients necessary for the crystallization of customary international law were not present until the April 14, 2018 United States/French/United Kingdom airstrikes on Syrian chemical weapons facilities. This Article examines the distinctive circumstances of the April 2018 airstrikes, including the context of a crisis of historic proportions, the focus on preventing the use of chemical weapons, the collectivity of the action taken, the limited targets and collateral damage, the explicit invocation of humanitarian intervention by the U.K. as the legal justification, and the U.S.’s apparent adoption of that justification. It explores whether these factors have rendered the April 2018 airstrikes a transformative event that may have changed international law concerning humanitarian intervention.