Next 9/11 shock might be being planned where we're not looking, UK's MI5 chief says

Domestic security service director warns against preparing to fight ‘yesterday’s enemy using yesterday’s methods,’ points to foiled plot to kill hundreds of Jews in Manchester

LONDON — Intelligence services must not dwell too much on past threats but accept that a new strategic shock along the lines of the September 11, 2001, terror attacks could already be in preparation where they are not looking, the head of Britain’s MI5 spy agency said.

In an opinion piece published on Friday to mark 25 years since al-Qaeda terrorists crashed hijacked US passenger planes into the World Trade Center in New York and the Pentagon, MI5’s Director General Ken McCallum said security agencies had to be ready to adapt to current and future challenges.

“We know that the next strategic shock will, by definition, not resemble the last one. That is perhaps the most important lesson of all,” McCallum wrote in the commentary for the Independent newspaper.

“We must of course always learn from the last attack — but must beware of preparing brilliantly to fight yesterday’s enemy, using yesterday’s methods, against yesterday’s target… The uncomfortable truth is that the next strategic shock may already be taking shape somewhere we are not yet looking.”

Al-Qaeda, though diminished, remains a threat, as does the aspiration of that group and other terrorists for mass casualty attacks, McCallum said.

This was recently borne out by a foiled Islamist plot to kill hundreds in gun attacks on the Jewish community in the northern English city of Manchester, he added.

But McCallum said MI5 was also facing rising state-backed aggression, ranging from sabotage carried out by criminal proxies to cyberattacks on power stations.

Weapons and ammunition rounds seized by police from the would-be perpetrators of a major antisemitic terror attack in the UK, who were convicted on December 23, 2025. (Greater Manchester Police)

Unlike in 2001, many systems and services are in the hands of the private sector, and it will require governments, businesses and academia working together to close vulnerabilities and respond swiftly in a crisis, he said.

“We cannot wait for the next shock to discover who owns the vulnerability, who has the authority to act, or who was supposed to pick up the phone,” he wrote.

“We owe the victims of 9/11 — and those who will otherwise become the victims of tomorrow’s attack — something more than remembrance. We owe them preparation, resilience and the courage to adapt before the next shock arrives.”

Times of Israel staff contributed to this report.