[381] In response to the unanimous passage of United Nations Security Council Resolution 1973 on March 17, Gaddafi—who had previously vowed to "show no mercy" to the rebels of Benghazi[382]—announced an immediate cessation of military activities.[383]
The next day, on Obama's orders, the U.S. military took part in air strikes to destroy the Libyan government's air defense capabilities to protect civilians and enforce a no-fly-zone,[384] including the use of Tomahawk missiles, B-2 Spirits, and fighter jets.[385][386][387] Six days later, on March 25, by unanimous vote of all its 28 members, NATO took over leadership of the effort, dubbed Operation Unified Protector.[388] Some Representatives[389] questioned whether Obama had the constitutional authority to order military action in addition to questioning its cost, structure and aftermath.[390][391] Obama later expressed regret for playing a leading role in the destabilization of Libya, calling the certain situation there "a mess."[392] He has stated that the lack of preparation surrounding the days following the government's overthrow was the "worst mistake" of his presidency.