Iran's unprecedented strikes on a US base in Qatar were carefully calculated to provide an exit from hostilities with Washington and set up a truce with Israel, according to analysts and an official.Monday's missile launches were signalled well in advance,

The Pentagon already had begun taking measures to strengthen its firepower in the Middle East and protect U.S. bases there.

Iran retaliated against the U.S. on Monday, launching missiles at a U.S. base in Qatar, according to a U.S. defense official and a statement from the Qatar foreign ministry. The missiles targeted Al Udeid Air Base outside Doha and were intercepted by air defenses before they could strike the base,