DUBAI, June 6 -- The first warning that the truce had failed again came from a radar screen, not a negotiating table. US air defense crews tracked four Iranian drones turning toward the Strait of Hormuz late Friday and shot them down before any reached the shipping lanes, the US military said.

Within hours the United States had struck two Iranian coastal radar installations, at Qeshm Island and Goruk, and Iran's Revolutionary Guard had fired seven missiles toward Kuwait and Bahrain. None of the missiles reached their targets, the US military said. What Friday established, again, is that the ceasefire both governments announced in April now survives mainly as a word they use to describe a war they are still fighting.

The drones "posed an...