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 statement from the Qatar foreign ministry. The missiles targeted Al-Ubaid Air Base outside Doha and were intercepted by air defenses before they could strike the base, the Qatari government said.

Iran has attacked a U.S. base in Qatar, calling the mission "Annunciation of Victory," according to Iranian state TV. The attack is focused on Al Udeid Air Base, according to the Islamic Revolutionary Guard Corps.