A ground assault by the Taliban killed the Islamic State militant who spearheaded the August 2021 suicide bombing at the Kabul airport that left 13 US troops and about 170 Afghans dead.
US officials said on Tuesday he was killed during a series of battles early this month in southern Afghanistan between the Taliban and the Islamic State group's affiliate.
US intelligence confirmed "with high confidence" that the Islamic State leader had been killed, a senior administration official said.
The officials spoke on condition of anonymity to discuss intelligence matters.
Over the weekend, the U.S. military began to inform the parents of the 11 Marines, the sailor and the soldier who were killed in the blast at Abbey Gate, and they shared the information in a private group messaging chat.
The father of one of the Marines said the death of his son's killer brings little comfort.
"Whatever happens, it's not going to bring Taylor back and I understand that," Darin Hoover, the father of Staff Sgt. Darin Taylor Hoover, said.
"About the only thing his mom and I can do now is be an advocate for him. All we want is the truth. And we're not getting it. That's the frustrating part."
Hoover said he and his son's mother, Kelly Henson, have spent the past year and a half grieving his death and praying for accountability from the Biden administration for the handling of the withdrawal.
He added that the Marines provided only limited information to him and did not identify the Islamic State leader or give the circumstances of his death.
The administration official said it was their "moral responsibility" to let the victims' families know that the "mastermind" and "person most responsible for the airport attack" had been taken off the battlefield.
The official added that intelligence officials determined that the leader had "remained a key plotter and overseer" for the group.
Several officials said the US played no role in the killing and did not coordinate at all with the Taliban.
The administration official called the Taliban action "significant" and said the US only learned of the operation through its "over the horizon" intelligence capabilities.
The fallen US service members were among those screening the thousands of Afghans frantically trying on Aug. 26, 2021, to get onto one of the crowded flights out of the country after the brutal Taliban takeover.
The scene of desperation quickly turned into one of horror when a suicide bomber attacked. The Islamic State group claimed responsibility.
The blast at Abbey Gate came hours after Western officials warned of a major attack, urging people to leave the airport.
But that advice went largely unheeded by Afghans desperate to escape the country in the last few days of an American-led evacuation before the US officially ended its 20-year presence.
The Afghanistan-based offshoot of the Islamic State - called Islamic State-Khorasan - has up to 4,000 members and is the Taliban's most bitter enemy and top military threat.
The group has continued to carry out attacks in Afghanistan since the Taliban takeover, especially against the country's minority groups.
White House National Security Council spokesman John Kirby said on Tuesday the US has "made clear to the Taliban that it is their responsibility to ensure that they give no safe haven to terrorists," whether from al-Qaida or the Islamic State.
"We have made good on the President's pledge to establish an over-the-horizon capacity to monitor potential terrorist threats, not only from in Afghanistan but elsewhere around the world where that threat has metastasized as we have done in Somalia and Syria," Kirby said in a statement.
