New Delhi, June 25 -- DUBAI - A week after a memorandum was supposed to quiet the most important stretch of water in the global oil trade, Iran spent Thursday reminding the world's tanker captains who they answer to. Its Revolutionary Guard Corps declared that a newly announced shipping lane through the Strait of Hormuz, drawn up without Tehran's involvement, was unacceptable and dangerous, and that no vessel should move through the channel without first calling the Guard's navy for clearance. The message was less about navigation than about authority, and about a war that has stopped without settling what it was fought over.

The dispute crystallizes the central ambiguity of the truce that ended four months of American and Israeli bombar...