The fall of Mokha was a lesson for Riyadh about alliances: the Mecca pact produced a courier, America’s older allies produced restrictions on American access, and the only partnership that has actually fought Iran’s network this year has an American hand on it. This is the lesson for Washington, and it has a date on it.

Consider the geometry the Houthis left behind. Hormuz is running at a fraction of pre-war volume — Tehran calls it closed, Washington insists it is open, and IMF PortWatch counted six transits on Sept. 6 against a pre-crisis norm of near 85 a day. The Houthis now hold the ground overlooking Bab el-Mandeb, and are threatening to close it altogether if Washington intervenes.