A ground assault by the Taliban killed the ISIS militant who spearheaded the August 2021 suicide bombing at the Kabul airport that left 13 US troops and about 170 Afghans dead during the chaotic US withdrawal from Afghanistan, US officials said Tuesday. Initially, neither the US — nor apparently the Taliban — were aware that the mastermind was dead. He was killed during a series of battles early this month in southern Afghanistan between the Taliban and the ISIS group’s affiliate, according to several officials. But in the past few days, US intelligence confirmed “with high confidence” that the ISIS leader had been killed, a senior administration official said. The officials spoke on condition of anonymity to discuss intelligence matters, The Associated Press said. Late Tuesday night, Pentagon press secretary Brig. Gen. Patrick Ryder issued a statement confirming that the plotter had been killed by the Taliban. “The United States was not involved in this operation," Ryder said. Over the weekend, the US 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 in a phone call with The Associated Press. “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 ISIS leader or give the circumstances of his death. US officials declined to provide many details because of sensitivities in the intelligence gathering. 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. Hoover is among a group of 12 Gold Star families that have kept in touch since the bombing, supporting one another and sharing information through the messaging chat. The chat was created by Cheryl Rex, the mother of Marine Lance Cpl. Dylan Merola, who died in the blast. Rex, who has been a vocal critic of the Biden administration’s handling of the withdrawal, told the AP it was through the chat group that they were informed late Monday about the killing as they awaited official confirmation from US military officials. The fallen 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 ISIS 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 ISIS 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. After the Trump administration reached a 2020 deal with the Taliban to withdraw US troops from Afghanistan and the Biden administration followed through on that agreement in 2021, there had been hope in Washington that the Taliban’s desire for international recognition and assistance for the country’s impoverished population might moderate their behavior. But relations between the US and the Taliban have deteriorated further since they imposed draconian new measures banning girls from school and excluding women from working for international aid and health agencies. However, a line of communication still exists between the two sides, led by the US special envoy for Afghanistan, Tom West. West’s contacts are primarily with Taliban officials in Kabul and not with the group’s more ideological wing based in Kandahar. The US decision to withdraw all troops fueled the swift collapse of the Afghan government and military, which the US had supported for nearly two decades, and the return to power of the Taliban. In the aftermath, President Joe Biden directed that a broad review examine “every aspect of this from top to bottom” and it was released earlier this month. The Biden administration in the publicly released version of the review largely laid blame on President Donald Trump for the deadly and chaotic 2021 withdrawal, which was punctuated by the suicide bombing at Abbey Gate. News of the killing came on the same day that Biden formally announced he will seek a second term as president, offering a reminder of one of the most difficult chapters of his presidency. The disastrous drawdown was, at the time, the biggest crisis that the relatively new administration had faced. It left sharp questions about Biden and his team’s competence and experience — the twin pillars central to his campaign for the White House. White House National Security Council spokesman John Kirby said 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 ISIS. “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. Yet Rex said the administration has not done enough to take responsibility for what happened at Abbey Gate. "I feel like this is the administration trying to get the pressure off of them for accountability by saying that we’re holding ISIS accountable for our kids’ death,” Rex said.