The United States killed al-Qaeda leader Ayman al-Zawahiri in a strike in Afghanistan over the weekend, US President Joe Biden said on Monday, the biggest blow to the militant group since its founder Osama bin Laden was killed in 2011.

Zawahiri, an Egyptian surgeon who had a $25 million bounty on his head, helped coordinate the September 11, 2001, attacks that killed nearly 3,000 people. 

US officials, speaking on the condition of anonymity, said Zawahiri died after a US drone strike in the Afghan capital Kabul at 6:18 a.m. on Sunday.

“Now justice has been delivered, and this terrorist leader is no more,” Biden said in remarks from the White House.

“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,” Biden said. 

US intelligence determined with “high confidence” through multiple intelligence streams that the man killed was Zawahiri, one senior administration official told reporters. He was killed on the balcony of a “safe house” in Kabul that he shared with other members of his family. There were no other casualties.

Biden said Zawahiri had been the mastermind behind or played a key role in attacks on the USS Cole and U.S. embassies in Kenya and Tanzania.

There were rumors of Zawahiri’s death several times in recent years, and he was long reported to have been in poor health, Reuters reported. 

The drone attack is the first known US strike inside Afghanistan since US troops and diplomats left the country in August 2021. 

His death raises questions about whether Zawahiri received sanctuary from the IEA following their takeover of Kabul in August 2021, Reuters reported. 

“The Taliban (IEA) will have to answer for al-Zawahiri’s presence in Kabul, after assuring the world they would not give safe haven to al-Qaeda terrorists,” Adam Schiff, chairman of the House Permanent Select Committee on Intelligence, said in a statement.

IEA  spokesman Zabihullah Mujahid meanwhile confirmed that a strike took place and strongly condemned it, calling it a violation of “international principles”.

Mujahid said in a series of tweets at first it was suspected that it was an explosion, but investigations by the security and intelligence agencies showed that the attack was carried out by an American drone. 

He said the IEA considers the action to be in violation of international principles and the Doha Agreement adding that it could severely damage relations between the two sides and “have bad consequences”.