A new 9/11 is coming any day, warns ex-MI6 spy

A former MI6 informant has warned that the risk of a major terrorist attack in the UK remains high, claiming there may be hundreds of potential Al-Qaida sleeper agents living in the country.

Aimen Dean, a former Al-Qaida member who later worked undercover for the UK’s Secret Intelligence Service for eight years, said the main threat to Western security comes from the spread of Islamist extremism and Iranian influence. He argued that governments are placing too much emphasis on Russia while underestimating other dangers.

“It’s not a question of if an attack like 9/11 or 7/7 will happen again, but when,” Dean said, warning that extremist networks remain active and capable of striking with little notice.

Dean claimed Iran should be a central focus of counterterrorism policy, alleging the country has supported extremist groups for decades. He said this support has enabled the development of sleeper cells that could be activated to carry out attacks, including against British citizens abroad. While he acknowledged it is impossible to give an exact figure, Dean estimated that the number of potential Al-Qaida affiliates in the UK could be in the hundreds.

He also predicted an increase in so-called “lone-wolf” attacks, arguing that extremist ideology continues to inspire individuals to act independently.

Dean’s background includes close contact with senior figures in Al-Qaida. As a teenager, he fought in the Bosnian war before travelling to Afghanistan, where he underwent training and associated with key members of the organisation. He later became disillusioned after the 1998 bombings of US embassies in East Africa, which killed hundreds of people, prompting him to leave the group.

After renouncing Al-Qaida, Dean was approached by MI6 and recruited as an intelligence asset. He later re-entered extremist circles while secretly passing information to British intelligence, helping to disrupt several major plots, including a planned attack on New York’s subway system.

Dean has said his undercover work placed him in constant danger, including moments when he feared his cover had been exposed. Eventually, his role was compromised following media reporting, forcing him to flee to the UK, where he was placed under protection and given a new identity.

He later detailed his experiences in a memoir, describing both his time inside Al-Qaida and his work with British intelligence agencies.