At the narrow throat of the Strait of Hormuz, where a third of the world's seaborne oil has long flowed as a matter of routine, that routine has now broken. Direct military strikes on commercial vessels by both American and Iranian forces have driven shipping traffic to its lowest point since May, marking a threshold moment in which state power is being openly exercised against the arteries of global commerce. The world's energy markets and shipping lanes are absorbing a lesson that has long been theorized but is now being lived: chokepoints are only stable until they are not.