The Biden administration took two potentially critical steps toward ending Saudi Arabia’s devastating war in Yemen on Thursday. First, national security advisor Jake Sullivan announced that it is ending US support for “offensive” Saudi military operations in Yemen. Second, Sullivan also announced the appointment of career foreign service officer Timothy Lenderking, previously a deputy assistant secretary in the State Department’s Near East Bureau, as a special Yemen envoy.

Ever since the Obama administration made the ill-advised decision to back the Saudi war effort against Yemen’s Houthi rebels back in 2015, the United States has owned substantial responsibility for what has become the greatest humanitarian catastrophe in the world. Tens of thousands of people or more (it’s virtually impossible to know how many at this point) have been killed violently in the conflict, with countless more wounded. Millions have either already died from or been left to struggle with rampant preventable disease (including COVID-19, whose effects have been similarly impossible to track, given the war and Yemen’s shattered public health infrastructure) and the lack of basic resources like food, medicine, and clean water.

Most of this suffering has been brought about by a brutal Saudi-led blockade and air campaign targeting Houthi-controlled northern Yemen, both of which have been made possible by US support. As a result, the United States has been liable in myriad Saudi actions that appear at least on their face to meet the definition of war crimes.