Behind the scenes, American intelligence and military officers have been working on clandestine plans, including the use of cyberattacks, to counter Iranian aggression without plunging into a full-out war, according to current and former officials.

How the pull-back happened: Our reporters describe Mr. Trump’s unusual decision-making process.

Retaliation: We learned that U.S. Cyber Command conducted online attacks last week against an Iranian intelligence group that U.S. officials believe helped plan recent attacks against oil tankers.

What’s next? The Trump administration is expected to present evidence to the U.N. Security Council suggesting that the American drone was in international air space when it was shot down by Iran — a point that Tehran disputes.

Response: Global leaders have urged both sides to de-escalate, calling on the U.S. to respond diplomatically to Iran.