(NewsNation) — President Joe Biden announced Monday evening the United States conducted a drone strike over the weekend that killed Al-Qaeda leader Ayman al-Zawahiri.

“Justice has been delivered,” Biden said in a prime-time address from the Blue Room Balcony at the White House. “This terrorist leader is no more.”

Al-Zawahiri was a doctor born in Egypt in 1951 and succeeded Osama bin Laden as the head of the terrorist group Al-Qaeda following his death at the hands of U.S. forces in 2011.

He was on the FBI’s Most Wanted Terrorist list for his alleged role in the 1998 bombings of the United States embassies in Dar es Salaam, Tanzania, and Nairobi, Kenya.

Al-Zawahiri was killed by the CIA drone strike shortly after 6 a.m. Monday in Kabul, Afghanistan, according to senior administration officials. Senior Taliban leaders knew al-Zawahiri was at the downtown Kabul safehouse, where he appeared on a balcony several times over the course of several months.

The reconnaissance operation was in the works for months, and Biden was briefed periodically during May and June, officials said. A formal, detailed briefing was given July 1, and the president was “deeply engaged” and asked questions about minimizing risks to civilians, according to officials.

“The United States continues to demonstrate our resolve and our capacity to defend the American people against those who seek to do us harm,” Biden said during his address. “If you are a threat to our people, the United States will find you and take you out.”

Biden authorized the strike last week, and he said there were no civilian casualties. There were no U.S. forces on the ground.

The death of al-Zawahiri comes one year after the withdrawal of U.S. troops from Afghanistan following more than 20 years of a presence there after the 9/11 attacks. The hasty and haphazard exit resulted in the deaths of 13 U.S. service members.

The Biden administration has said it would continue to conduct counterterrorism operations using “over the horizon” operations, commonly known as drone strikes.

Senior administration officials said the Taliban tried to cover up evidence that al-Zawahiri was killed in the operation. The United States did not alert the Taliban before the strike, officials said.

This is a breaking news story. Please check back for updates.