Biden said in live remarks from the Blue Room Balcony at the White House: "I authorized a precision strike that would remove him from the battlefield." "There were no civilian casualties."

Al-Zawahiri, 71, became head of Al-Qaeda in 2011 after its longtime leader Osama bin Laden was shot and killed by US forces in Abbottabad, Pakistan during a raid.

Biden's announcement came nearly a year after the US military completed a withdrawal from Afghanistan that it invaded in response to the 9/11 terrorist attacks carried out in 2001 by Al-Qaeda operatives against targets on American soil, which killed nearly 3,000 people.

"He was deeply involved in the planning of 9/11," Biden said of Al-Zawahiri. "He coordinated al-Qaeda's branches and all around the world, including setting priorities for providing operational guidance that called for and inspired attacks against US targets."

A senior administration official briefed reporters that the drone strike was conducted in Kabul on Sunday morning with hellfire missiles that targeted and killed Al-Zawahiri, who was standing on the balcony of a safe house.

Preparation for the operation was said to have taken months. Biden gave the final authorization on July 25 while quarantined at the White House due to a COVID-19 infection, according to the official. — Agencies