President Joe Biden is expected to address the nation from the White House as 7:30pm Eastern about the operation that killed one of the world’s most-wanted terrorists, Ayman al-Zawahiri.

“Over the weekend, the United States conducted a counterterrorism operation against a significant Al Qaeda target in Afghanistan,” a senior administration official told Fox News Monday. “The operation was successful and there were no civilian casualties.”

Two intelligence sources tell Fox News Al Qaeda leader Ayman Al Zawahiri was killed in the CIA drone strike.

The United States has killed Ayman al-Zawahiri, the leader of al-Qaeda and one of the world’s most-wanted terrorists, who oversaw the attacks of Sept. 11, 2001, alongside the group’s founder, Osama bin Laden, according to U.S. officials familiar with the matter.

Both men escaped U.S. forces in Afghanistan in late 2001, and Zawahiri’s whereabouts had long been a mystery. Bin Laden was killed in a raid by U.S. forces in Pakistan in 2011.

The Associated Press first reported that Zawahiri was killed.

It was not immediately clear where and when Zawahiri died and what element of the U.S. government had carried out the mission. The White House said on Thursday that President Biden would give remarks in the evening about “a successful counterterrorism operation” but did not mention Zawahiri.