MI5 chief warns next 9/11-scale attack could be brewing where no one is watching

The head of Britain's Security Service MI5, Ken McCallum, issued a rare public statement on Friday to mark the 25th anniversary of the September 11, 2001 terrorist attacks. He warned that planning for the next attack on a similar scale could already be underway in a place currently outside the attention of security services.

In an opinion piece for The Independent, McCallum stressed that the next major strategic shock will, by definition, not resemble the last one. While learning from past attacks remains essential, he cautioned against the mistake of preparing only to fight yesterday's enemy using yesterday's methods and defending yesterday's targets.

A call for cooperation

The MI5 chief noted that, unlike in 2001, much of today's security infrastructure and services are managed by the private sector, meaning that preventing future attacks requires broader collaboration. McCallum called on government, businesses, academia and the public to treat national security not as the narrow responsibility of a few agencies, but as a shared, nationwide effort.

Threats remain active

Although Al Qaeda has been significantly weakened over the past 25 years, it still poses a threat, as do other terrorist groups seeking to carry out mass-casualty attacks, McCallum warned. He cited a recently foiled Islamist plot to kill hundreds of people within Manchester's Jewish community in northern England as an example. He also pointed to growing state-backed aggression, ranging from sabotage carried out by criminals acting as proxies to cyberattacks on power stations.

The MI5 director said terrorist ambitions to cause mass casualties have not disappeared, but now exist alongside strategic national security threats posed by capable and influential states. His statement came as the United States marked the 25th anniversary of the September 11 attacks on the World Trade Center and the Pentagon, which killed nearly 3,000 people and have since claimed thousands more lives due to related health problems.