WASHINGTON: A deadly attack in Afghanistan's capital Kabul on Thursday was carried out by a single suicide bomber at a gate to the airport and there was no second explosion at a nearby hotel, the Pentagon said on Friday.

The Kabul airport attack on Thursday, which killed 13 US troops and at least 79 Afghans, was claimed by Islamic State militants. The Islamic State's Afghan affiliate, ISIS-Khorosan, has emerged as an enemy of both the West and of the Taliban.

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"I can confirm for you that we do not believe that there was a second explosion at or near the Baron Hotel, that it was one suicide bomber," Army Major General William Taylor told reporters. He said US troops wounded in the attack were now being treated in Germany.

Pentagon spokesman John Kirby told the reporters the United States believed there are still "specific, credible" threats.

"We certainly are prepared and would expect future attempts," Kirby said, adding: "We're monitoring these threats, very, very specifically, virtually in real time."

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Thursday's attack occurred during a US-led evacuation of tens of thousands of people. The Taliban came to power nearly two weeks ago as foreign forces began withdrawing, ending a 20-year war.

US General Frank McKenzie, the head of US Central Command, had said on Thursday that initial information was that two suicide bombers had attacked the airport gate and the nearby Baron hotel.