Security forces in the United States have killed Al-Qaeda leader Ayman al-Zawahiri in an airstrike in Kabul, President Joe Biden claimed on Monday.

Al-Zawahiri had been accused of plotting the September 11, 2001, terrorist attacks, also known as 9/11, in the United States along with former Al-Qaeda chief Osama Bin Laden.

On Monday, Biden said that the United States conducted an airstrike in Kabul, Afghanistan two days ago, killing al-Zawahiri. He added that the killing will bring closure to the families of those who died in the attacks.

The Al-Qaeda leader was on the balcony of his hideout in the Afghanistan capital when he was killed by two Hellfire missiles launched from an unmanned drone, according to the Associated Press.

None of al-Zawahiri’s family members were hurt in the operation, and there were no civilian casualties, the United States president said. “This mission was carefully planned and rigorously minimized the risk of harm to other civilians,” he said.

The Central Intelligence Agency, the United States’ foreign intelligence service, carried out the strike, AP reported, citing five unidentified persons familiar with the matter. While Biden did not specifically mention the CIA, he expressed gratitude to the country’s “intelligence community and counterterrorism communities” for the success of the operation.

“The United States continues to demonstrate our resolve and our capacity to defend the American people against those who seek to do us harm,” he said. “No matter how long it takes, no matter where you try to hide, we will find you.”

A spokesperson for the Taliban said that the United States airstrike was a violation of international principles, the BBC reported. “Such actions are a repetition of the failed experiences of the past 20 years and are against the interests of the United States of America, Afghanistan and the region,” the spokesperson said.

Al-Zawahiri took over Al-Qaeda after Bin Laden was killed by United States security forces on May 2, 2011. In recent years, al-Zawahiri’s influence had been shrinking because of increased activity of outfits such as the Islamic State.

Al-Zawahiri’s involvement in terror attacks

On September 11, 2001, Al-Qaeda operatives had hijacked four planes, two of which two crashed into the North and South towers of the World Trade Center. Both the towers collapsed in an hour. Another plane crashed into a portion of the Pentagon. The fourth plane, which was allegedly intended to destroy another important building, crashed into a field in Pennsylvania. The attacks killed 2,977 persons.

Biden said on Monday that al-Zawahiri, before 9/11, was involved in a suicide bomb attack on naval destroyer USS Cole in Aden in October 2000, which had killed 17 sailors.

The Al-Qaeda was also alleged to have been involved in the bombings of United States embassies in Kenya and Tanzania in 1998, which killed 224 persons and left over 4,500 wounded.