The succession of Al-Qaeda leader Ayman Al-Zawahiri, who was believed to have been killed in a US raid last year, remains unclear, a US intelligence official said on Tuesday, according to Reuters.
US President Joe Biden confirmed last August that Al-Zawahiri had been killed in a US air strike in Afghanistan.
Biden said he authorized the strike on “clear and convincing evidence” of Al-Zawahiri’s location, and added that none of Al-Zawahiri’s family members were hurt and there were no civilian casualties.
Reports said that Al-Zawahiri was killed by two missiles fired from a drone in the skies over his Kabul home.
The Taliban later claimed it has not found the body of al-Zawahiri and is continuing its investigations into the matter.
"The question for Al-Qaeda, that it has not answered for itself, is who follows (Zawahiri)," Christine Abizaid, director of the US National Counterterrorism Center, said on Tuesday in an event organized by the Washington Institute when asked about Al-Qaeda's "center of gravity" after Zawahiri's death.
Al-Qaeda has not named a successor, though Saif al-Adel, a mysterious, low-key former Egyptian special forces officer who is a high-ranking member of Al-Qaeda, is seen by experts as the top contender. The United States is offering a reward of up to $10 million for information leading to his arrest.
Abizaid also said that Americans must remain vigilant about overseas-based extremist organizations such as Al-Qaeda and Islamic State.
"The online environment is where most of the radicalization is occurring," she said, according to Reuters.
Lone actors remained a key threat for the United States, Abizaid said, adding they could be inspired by overseas extremist groups or be driven by racially and ethnically motivated violent domestic extremism.