The bombing had left at least 170 people dead.

The bombing occurred at a time when people were fleeing the war-torn nation after the Taliban had taken control of Kabul.

The IS figure was killed weeks ago but it took time to confirm his death, US officials told BBC news partner CBS.

The White House says it will not release the name of the man, but described him as the "mastermind" of the assault on Abbey Gate, one of the main points of entry for those trying to evacuate Afghanistan during the U.S. withdrawal, reports CBS News.

Officials learned of his death in Afghanistan weeks ago, but said it has taken some time to confirm.

"Experts in the government are at high confidence that this individual…was indeed the key individual responsible" for the attack outside Hamid Karzai International Airport on Aug. 26, 2021, a senior administration official told CBS News.

The U.S. was not informed about the death by the Taliban, but it made the determination from its own intelligence gathering and monitoring of the ongoing threats and actors in the region.

"This was a Taliban operation. We didn't conduct it jointly with them or anything like that," the U.S. official told CBS News. U.S. law prohibits military cooperation and military intelligence sharing with the Taliban.