Al Zawahiri, one of the masterminds of the 9/11 attacks, was killed in a US drone strike at his home in the Afghan capital, where he was hiding with his family. White House national security spokesman John Kirby told CNN: “We have no DNA confirmation. We are not going to receive this confirmation. “Honestly, based on multiple sources and methods we’ve gathered information from, we don’t need it. “We have visual confirmation, but we also have confirmation through other sources.” Read more: From middle-class doctor to world’s most wanted – who was Ayman al-Zawahiri? US President Joe Biden announced the death from the balcony of the White House Blue Room, saying “justice has been served”. “This terrorist leader is no more,” Biden added, before expressing his hope that the assassination would bring “another measure of closure” to the families of the nearly 3,000 people who died in the Sept. 11, 2001, attacks. The president added that Afghanistan “will never again become a safe haven for terrorists” after the strike, which came almost a year after US troops left the country. Use Chrome browser for more accessible video player 1:11 Biden: “This terrorist leader is no more” The Egyptian terror leader was standing on the balcony of a bunker on Sunday morning when he was killed by two inferno missiles fired from a drone. Biden said none of the 71-year-old’s family members were injured and there were no civilian casualties. The FBI had offered $25 million for “information leading to the arrest or conviction” of the terror leader, whose death is the biggest blow to al-Qaeda since its founder Osama bin Laden was killed by US special forces. USA in 2011. According to a senior US administration official, the operation to kill al-Zawahiri was months in the planning. Mr Biden was first informed of a proposed operation to kill the Al Qaeda leader on July 1 this year. But it was much earlier in the year when reports suggested that his wife and children had moved to Kabul. He and his family were believed up until that point to be hiding in Pakistan. The family was in a shelter where, the US official says, al-Zawahiri was eventually located. Image: The suspicious house in Kabul that was hit by a US drone He was followed for several months and his lifestyle was recorded. He never left the house but spent time on a balcony where he was eventually killed. On July 25, a detailed proposal was presented to Mr. Biden, who, the administration official said, called for “a great deal of interest” because of the focus on taking “every step … to minimize civilian casualties.” Use Chrome browser for more accessible video player 0:30 Smoke after strike on terror chief The information allowed the Americans to study the construction of the house to ensure that civilian casualties were avoided. The official added that al-Zawahiri’s death is “a significant blow to al-Qaeda and will degrade their ability to operate.”