The ISIS leader responsible for the planning of the 2021 attack at the Kabul airport that took the lives of 13 U.S. service members has been killed by the Taliban, a Defense Department spokesperson confirmed to CBS News late Tuesday night. 

Brig. Gen. Patrick Ryder, Pentagon press secretary, told CBS News in a statementthat the Defense Department could confirm that he was killed by the Taliban in Afghanistan "in early April," adding that the U.S. "was not involved in this operation."

This comes after Senior Biden administration officials earlier Tuesday confirmed the ISIS leader's death, but said the White House would not release the name of the man, describing 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. 

Officials learned of his death in Afghanistan weeks ago, but said it had 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. More than 100 Afghan civilians were also killed in the suicide bombing.

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 said. U.S. law prohibits military cooperation and military intelligence sharing with the Taliban. 

Asked why the U.S. government was certain this was the individual responsible for the bombing, and how that determination was made, the official said he could not provide further detail.  

CBS News learned on Monday that the Pentagon had started notifying families of the deceased service members killed in the explosion. The White House asked CBS to hold its reporting until all 13 families had been directly notified. 

Darin Hoover, father of Marine Staff Sgt. Taylor Hoover, said he was notified by the Marine Corps Tuesday. 

"They could not tell me any details of the operation, but they did state that their sources are highly trusted, and they've got it from several different sources that this individual was indeed killed," Hoover said in an interview Tuesday.

"This might be the sort of circumstances in which ordinarily we might not say anything at all. But we do think that it's important to offer this, especially to families who obviously have suffered the unimaginable," the senior administration official told CBS News. "And no one expects that this will bring an end to the suffering the one experiences when one loses a loved one."

Word of the ISIS leader's death comes as Mr. Biden launches his 2024 re-election campaign. In 2020, he had campaigned on a vow to end the war in Afghanistan, but also cast himself as a leader capable of restoring competence to government management and U.S. foreign affairs.

The airport attack, coupled with images of the hasty, chaotic withdrawal and later,  a meeting with the families of the deceased service members that at times turned confrontational, damaged that perception and caused his overall approval rating to plummet. 

Administration officials dismissed any suggestion that the timing of the announcement coincided with the president's reelection plans. One said the timing was purely coincidental. 

President Biden vowed retribution for the attack, saying in August 2021, "We will not forgive. We will not forget. We will hunt you down and make you pay." 

Three days later, however, a U.S. military drone strike intended to kill ISIS-K leaders ended up killing 10 civilians, including seven children, the Pentagon later admitted. 

Cheryl Rex, the mother of Marine Lance Cpl. Dylan Merola, said that incident makes her question the identity of the individual killed and the veracity of the administration's claims surrounding his death. 

"They've told us before they've already killed the person that was in charge, and then when they came back with the report saying it was a civilian with his children," Rex said. "I would like to see them imprisoned. They have 13 counts of murder on their hands." 

Military leaders initially said the strike was conducted based on an imminent threat to U.S. personnel after the airport bombing. After U.S. Central Command concluded civilians were killed, top brass called it "a terrible mistake" but said they had relied on credible intelligence of an imminent threat at the airport.

ISIS-K has carried out regular attacks on the Taliban regime that reclaimed power in Afghanistan as the U.S.-led military alliance pulled out of the country in the summer of 2021. The devastating attack on the airport came as U.S. and other Western forces used the facility as a coordination and exit point for the chaotic withdrawal. 

Eleanor Watson and Arden Farhi contributed to this report. 

Christina Ruffini

CBS News correspondent