At least a dozen U.S. troops were killed and several others wounded in Thursday's suicide bombings at Kabul airport, sources claimed, in what the Pentagon said was a "complex attack" during its evacuation mission from Afghanistan.
In a statement, Pentagon Spokesman John Kirby confirmed multiple U.S. fatalities but did not give details. The U.S. servicemembers were among those killed when at least two blasts tore through crowds thronging the airport gates.
Two U.S. officials, speaking on condition of anonymity, told Reuters that at least a dozen U.S. personnel were killed. Officials said that number could change and was expected to increase. Several other U.S. troops were wounded, the officials said.
A Taliban official said at least 22 people including children had been killed in the attack and 52 were wounded, though it was clear from video footage that those figures could be as high as 70.
In a statement, Islamic State claimed responsibility and said one of its suicide bombers had targeted "translators and collaborators with the American army".
U.S. General Frank McKenzie, head of U.S. Central Command, told reporters in a briefing that the threat from Islamic State persisted alongside "other active threat streams".
The suicide bombing attacks came after the United States and allies urged Afghans to leave the area around the airport because of a threat by Islamic State militants.
The U.S. military death toll in the Afghanistan war since 2001 stood at roughly 2,500.
In an alert issued on Wednesday, the U.S. Embassy in Kabul had advised citizens to avoid traveling to the airport and said those already at the gates should leave immediately, citing unspecified "security threats."
A source familiar with U.S. congressional briefings said U.S. officials strongly believe that the Afghan affiliate of Islamic State, known as Islamic State Khorasan (ISIS-K), after a historic name for the region, was responsible. ISIS-K is opposed by the United States and the Taliban.
Kirby said one blast occurred near the airport's Abbey Gate and the other close to the nearby Baron Hotel.
"The explosion at the Abbey Gate was the result of a complex attack that resulted in a number of US & civilian casualties," Kirby said on Twitter.
A massive airlift of foreign nationals and their families as well as some Afghans has been under way since the day before Taliban forces captured Kabul on Aug. 15, capping a swift advance across the country as U.S. and allied troops withdrew.
The United States has been racing to carry out the airlift before its military is set to fully withdraw from the country by Aug. 31. There was no indication from the White House that Biden plans to change the Aug. 31 withdrawal target as a result of the attacks, a source familiar with the situation told Reuters.
Biden was in a meeting with security officials about the situation in Afghanistan, where the United States is in the final steps of ending its 20-year war, when the explosions were reported, according to a person familiar with the matter.
Biden, Secretary of State Antony Blinken, Defense Secretary Lloyd Austin, Joint Chiefs of Staff Chairman General Mark Milley and Vice President Kamala Harris monitored events via video links.
A Western diplomat in Kabul said that areas outside the airport gates had been "incredibly crowded" again despite the latest warnings.
The United States and its allies have mounted one of the biggest air evacuations in history, bringing out about 95,700 people, including 13,400 on Wednesday, the White House said on Thursday.
Blinken said on Wednesday that there were still about 1,500 U.S. citizens in Afghanistan, and that at least 4,500 U.S. citizens had already been evacuated from the country.