Washington, April 26 : US officials have said that the Islamic State (IS) terror group mastermind thought to have planned the devastating 2021 bombing at the Kabul airport has been killed by Afghanistan's ruling Taliban government. According to multiple media reports, the US identified the suspect as a leader within the terror group's Afghan branch known as IS-K, but didn't name the individual and refused to reveal how this person was killed, for fear that doing so would jeopardise American intelligence-gathering capability in the region, reports Xinhua news agency. The individual was "the mastermind of the horrific attack" on August 26, 2021 that killed 13 US service members as well as 170 Afghan civilians. John Kirby, coordinator for strategic communications at the National Security Council, was quoted by CNN as saying, referring to it as one of a "series of high-profile leadership losses" that IS-K has suffered this year. The US was not involved in the Taliban's operation, nor was it notified by the regime about the death, the reports said. Confirmation of the person's death and identity was based on the US' own intelligence gathering. The administration reportedly began calling relatives of the US troops killed in the suicide bombing to inform them of the suspect's death, but its refusal to disclose further details left one relative frustrated. "They couldn't give me his name; they couldn't tell me the details of the operation," Darin Hoover, the father of Taylor Hoover of the US Marine Corps, was quoted by The New York Times as saying. Dissatisfied about the inadequate information he got from the government, Hoover said the call left him feeling "frustrated, again". The death of the suspect "doesn't absolve the administration or the State Department or the Pentagon from taking responsibility or accountability for what happened, Hoover was quoted by CNN as saying. They haven't stepped up and said we messed this up and it won't happen again". "And I personally think it can happen again," he added. Three days after the Kabul airport attack, the US launched a drone strike on August 29, 2021, hitting a white Toyota the officials believed at the time was loaded with explosives. It later became clear that what were inside the car turned out to be water containers, and that those killed by the US Hellfire missile were not terrorists, but 10 Afghan civilians, including seven children. The August 2021 pull-out of US troops from Afghanistan marked the end of America's longest war. It led to the collapse of the Afghan government and military, which the US government had supported for two decades. It also led to the return of power to the Taliban. The Biden administration was criticised both at home and abroad in the aftermath of the pull-out. Many had expressed anger over the abandonment of Afghans and of US weaponry, and one US Marine injured in the blast described the pull-out as a "catastrophe" during Republican-led hearings examining the withdrawal. /IANS