At the height of the widely critiqued and chaotic withdrawal of U.S. forces from Afghanistan came a deadly terrorist bombing outside the airport in Kabul that killed 13 U.S. service members and 170 Afghans while wounding scores more on August 26, 2021.

Reports now indicate that the alleged Islamic State group leader who masterminded that deadly plot was killed this month by the Taliban that now rules Afghanistan, according to the Daily Mail.

Family members of the 13 American victims -- 11 U.S. Marines, one U.S. Navy sailor, and one U.S. Army soldier -- began to be informed of the news over the weekend and then proceeded to spread the word amongst themselves in a special private messaging chat group.

Taliban killed terror bombing plotter

The Associated Press reported that the August 26, 2021 suicide bombing attack occurred outside what was known as the Abbey Gate of the Hamid Karzai International Airport in the capital city of Kabul while U.S. forces watched over a chaotic evacuation of foreign allies, U.S. citizens, and Afghan partners and supporters.

The bomb used was believed to have contained approximately 20 pounds of explosives and was packed with ball bearings that became destructive shrapnel and led to at least 45 U.S. service members suffering injuries in addition to the 13 that were killed.

Almost immediately after the bombing occurred, the Islamic State group offshoot in Afghanistan -- known as Islamic State-Khorasan or ISIS-K -- claimed credit for the deadly blast.

According to unnamed U.S. officials, the purported mastermind behind that blast, who has not yet been identified, was killed in early April by the Taliban during a military operation in southern Afghanistan against the ISIS-K terrorists, though it is not believed that the Taliban were aware of the identity of terror leader at that time.

The AP noted that ISIS-K, which is suspected to have around 4,000 members, is an avowed enemy of the Taliban that has continued to conduct bombings and other deadly attacks against the ruling government, Afghan civilians, and minority groups across the country since the U.S. completed its withdrawal just days after the suicide bombing at the airport.

Death of ISIS-K leader confirmed

Axios reported that President Joe Biden's administration has not yet released the name of the ISIS-K leader suspected of plotting the bombing attack outside the Kabul airport but has confirmed that he was killed by the Taliban earlier this month.

Brig. Gen. Patrick Ryder, the Pentagon’s press secretary, told the outlet on Tuesday that the U.S. had no involvement in that operation but nonetheless "can confirm that the senior ISIS-Khorasan plotter responsible for planning" the bombing was now deceased.

Similarly, National Security Council spokesman John Kirby confirmed to Axios that the individual killed by the Taliban "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."

The outlet further noted that ISIS-K, which arose in Afghanistan in 2014 shortly after the Islamic State group in Iraq and Syria began conquering territory, swore its allegiance to leader Abu Bakr al-Baghdadi, who was killed in a U.S. operation in Syria in 2019, and carried out attacks against both U.S. and allied forces and the Taliban in the years since then.

According to Thomas West, the Biden administration's envoy to Afghanistan, the ISIS-K group is considered to be a "common enemy" of both the U.S. and the Taliban, though it is unclear how much, if any, cooperation there has been in going after that terrorist organization.

Biden admin shifts blame, not forthcoming with answers for victims' families

In early April, around the same time as the apparent Taliban operation that killed the ISIS-K leader, President Biden's White House issued a review of the events before and during the August 2021 effort to withdraw all U.S. forces from Afghanistan, and while it did appear to include some lessons learned from the chaotic evacuation operation, it largely cast blame for what went wrong on the prior administration of former President Donald Trump.

With regard to the bombing, the report noted that the threat of an attack at the crowded gates outside the airport was known but deemed to be a "manageable risk" and the decision was made to keep the targeted Abbey Gate open in order to continue evacuating U.K. personnel and Afghan allies.

The report also made note of a drone strike in northern Afghanistan one day after the bombing at the airport that was believed to have killed "two high-profile ISIS-K individuals" followed by a second drone strike inside Kabul a couple of days later that killed 10 civilians, including several young children, that was determined to be a "tragic error" and, according to the AP, an "honest mistake" due to the belief of an "imminent threat" of additional bombing attacks.

Dan Hoover, the father of airport bombing victim Marine SSgt. Darin Taylor Hoover, told the AP in response to the news of the slain ISIS-K leader, "Whatever happens, it’s not going to bring Taylor back and I understand that. 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."