The barrage was intercepted without casualties, potentially allowing Iran to save face while avoiding further retaliation from Washington.

Although the operation achieved an impressive level of tactical success, with a swarm of warplanes penetrating Iran unchallenged following a long, undetected flight from Missouri, it will be far harder than the president has suggested to reliably evaluate the damage inflicted on Iran’s ability to manufacture a nuclear weapon.

As Mr. Trump last week weighed whether to use direct military force against Iran, a bipartisan contingent of lawmakers demanded that the president seek congressional approval before moving forward with any action.