In the contested waters of the Persian Gulf, the ancient logic of retaliation has once again asserted itself — the U.S. military struck three Iranian oil tankers on Saturday, destroying one and damaging two, in response to prior attacks on American warships. The action marks not merely an exchange of fire, but a quiet crossing of thresholds: commercial shipping, long treated as a separate domain from military confrontation, has now entered the calculus of war. Humanity has long struggled to contain conflict within agreed boundaries, and each boundary crossed makes the next one easier to breach