(NewsNation) Iran launched a missile attack on a U.S. military base in Qatar, in retaliation for the American bombing of its nuclear sites.The United States on Monday previously said it was closely monitoring potential threats after explosions were heard in Qatar.I can confirm that al Udeid Air Base was attacked by short-range and medium-range, ballistic missiles originating from Iran today at this time there are no reports of US casualties," a U.S. Defense official told NewsNation. "We are monitoring the situation closely and will provide more information as it becomes available.US-Iran conflict: What are some of the resistance groups?The attack came shortly after Qatar closed its airspace as a precaution amid threats from Iran. Iran acknowledged the missile barrage on Qatar was the same number as bombs used by the U.S. on nuclear sites, signaling a desire to de-escalate."We express the State of Qatar's strong condemnation of the attack on Al Udeid Air Base by the Iranian Revolutionary Guard Corps, and consider it a flagrant violation of the State of Qatar's sovereignty and airspace, as well as of international law and the United Nations Charter, said a Qarar Ministry of Foreign Affairs spokesperson. "We affirm that the State of Qatar reserves the right to respond directly in a manner proportional to the nature and scale of this blatant aggression and in accordance with international law."Trump hits Iran: 5 questions on what comes nextIran, in the past, has threatened American forces at Al Udeid Air Base, which hosts the forward headquarters of the U.S. militarys Central Command. Before the attack, Israel also expanded its war against Iran to include targets associated with the countrys struggling theocracy.Qatar's Ministry of Defense says that the country's air defense successfully intercepted a missile attack on the al Udeid Air Base.The Gulf nation of Bahrain, home to the U.S. 5th Fleet headquarters, says it is temporarily suspending flights in its airspace.