The United States was sending B-52 bombers, AC-130 gunships and fighter jets into Afghanistan Saturday to turn back dramatic recent advances by the Taliban.

The Boeing B-52 Stratofortress bombers, the mainstay of American strategic airpower since 1952, were flying into Afghanistan from al-Udeid airbase in Qatar, The Times of London reported, citing Defense Department sources.

The nuclear-powered aircraft carrier USS Ronald Reagan, stationed in the Arabian Sea, is contributing its F/A-18 Super Hornet fighter jets to the missions, but they are not involved in the bombing, the report states. Lockheed AC-130 Spectre attack planes, dubbed “the world’s deadliest gunship,” have also been sent into action.

The onslaught of American airpower comes as the Taliban makes territorial gains throughout Afghanistan in the wake of the near-total departure of U.S. forces ordered by President Biden.

The city of Zaranj in Nimroz, a southwest province bordering Iran, was overrun by the Taliban Friday, making it the first provincial capital to fall since foreign troops began their withdrawal. Meanwhile, insurgents in the Afghan capital of Kabul, assassinated Dawa Khan Menapal, the government’s chief media officer, according to sources.

The deteriorating security situation forced the US Embassy on Saturday to urge American citizens to leave Afghanistan immediately.

“The defense sources insisted that there was every intention to continue with the airstrikes after August 31, the date set for the withdrawal of the last remaining US troops in Afghanistan,” the Times reports.