Iranian Foreign Ministry spokesperson Esmaeil Baqaei said the strikes were a direct response to what Tehran called “unprovoked aggression against Iran’s territorial integrity and national sovereignty” by the United States.

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.