"I authorized a precision strike that would remove him from the battlefield, once and for all," Biden said.
Zawahiri, who had just turned 71 years old, had stayed a notable international symbol of the group 11 years after the U.S. killed Osama bin Laden. At one time, he acted as bin Laden's personal physician.
Zawahiri was hiding in downtown Kabul to join his family, Biden said, and was killed in what a senior administration official described as "a precise tailored airstrike" using two Hellfire rockets. The drone strike was conducted at 9:48 p.m. ET on Saturday was confirmed by Biden following weeks of meetings with his Cabinet and key advisers, the official said on Monday, adding that no American staff were on the ground in Kabul at the time of the attack.
Senior Haqqani Taliban numbers were conscious of Zawahiri's presence in the area, the official said, in "clear violation of the Doha agreement," and even took measures to hide his presence after Saturday's successful strike, limiting access to the safe house and quickly transferring members of his family, including his daughter and her children, who were intentionally not targeted during the strike and remained intact. The U.S. did not inform Taliban officials before Saturday's strike.
In a series of tweets, Taliban spokesman Zabiullah Mujahid said, "An air strike was carried out on a residential house in Sherpur area of Kabul city on July 31."
He said, "The nature of the incident was not apparent at first" but the security and intelligence services of the Islamic Emirate investigated the incident and "initial findings determined that the strike was carried out by an American drone."
The tweets by Mujahid came out before CNN reported Zawahiri's death. Mujahid said the Islamic Emirate of Afghanistan "strongly condemns this attack on any pretext and calls it a clear violation of international principles and the Doha Agreement."
Biden, who was kept up-to-date regarding the strike against Zawahiri as he was isolated with a rebound case of Covid-19, spoke outdoors Monday from the Blue Room Balcony at the White House.
Zawahiri, Biden said, "was deeply involved in the planning of 9/11, one of the most responsible for the attacks that murdered 2,977 people on American soil. For decades, he was the mastermind of attacks against Americans."
"Now, justice has been delivered and this terrorist leader is no more. People around the world no longer need to fear the vicious and determined killer," he continued. "The United States continues to demonstrate our resolve and our capacity to defend the American people against those who seek to do us harm. We make it clear again tonight, that no matter how long it takes, no matter where you hide, if you are a threat to our people, the United States will find you and take you out."