New Delhi, June 16 -- This article has been lightly updated.

ON ROUGHLY 40 OCCASIONS since March, Donald Trump has claimed that he was close to a deal with Iran. This time, he was, at last, right. Overnight on Sunday both America and Iran announced an agreement that they claim will end their nearly four-month war and reopen the Strait of Hormuz. It will bring needed relief to a scarred region, and to global energy markets. But it will not resolve the issues that brought America and Iran to war in the first place.

The preliminary agreement, which the Americans describe as a memorandum of understanding (MOU), was signed on Monday. An official signing ceremony is scheduled to take place on Friday in Geneva. Until then the text will probabl...