WASHINGTON, April 25 (Reuters) - The Taliban have killed an Islamic State militant who was the "mastermind" behind a suicide attack at Kabul's international airport in 2021 that killed 13 U.S. troops and scores of civilians during the United States' chaotic evacuation from the country, U.S. officials said on Tuesday.

The bombing occurred on Aug. 26, 2021, as U.S. troops were trying to help Americans and Afghans flee in the chaotic aftermath of the Taliban's takeover, and compounded America's sense of defeat after 20 years of war.

"He was a key ISIS-K official directly involved in plotting operations like Abbey Gate, and now is no longer able to plot or conduct attacks," White House spokesperson John Kirby said in a statement, referring to the Abbey Gate entrance to the Kabul airport where the blast occurred. He did not name the official.

The Afghan affiliate of Islamic State, known as Islamic State Khorasan or ISIS-K, after an old name of the region, is an enemy of the Taliban. Fighters loyal to Islamic State first appeared in eastern Afghanistan in 2014 and later made inroads in other areas.