DUBAI, June 28 -- The truce was seventeen days old when the bombs fell. On Friday, American warplanes struck Iranian territory for the first time since the two governments signed the Burgenstock memorandum that was meant to end the fighting, and in doing so Washington answered a question that has hung over the Gulf since the ink dried. The peace it brokered is only as durable as its own restraint.

Six American aircraft hit four sites along Iran's southern coastline, US Central Command said, describing the operation as a "powerful response" to what it called Iran's "unwarranted aggression" in the Strait of Hormuz a day earlier. Iran did not wait long to reply. The naval arm of the Islamic Revolutionary Guard Corps said it had already stru...