Pakistan, July 18 -- The joint call by China and Pakistan for the United States and Iran to end hostilities and resume dialogue arrives as terrifying attacks have spread again across southern Iran and the Gulf.

That the immediate burden lies on Washington and Tehran cannot be stressed enough. Each says it is responding to the other's breach of the Islamabad Memorandum signed in June and each regards coercion as a means of improving its negotiating position. Yet the past fortnight has shown the poverty of that calculation. American strikes have reached the Iranian coast and islands, while Iranian missiles and drones have put Gulf states hosting US forces on alert. The threshold between a contest over maritime passage and a region-wide con...