MI5 chief warns next 9/11-style attack could be planned where we are not looking

Intelligence services must not dwell too much on past threats but accept that a new strategic shock along the lines of the 9/11 attacks could already be in preparation where they are not looking, the head of Britain's MI5 spy agency said.

Ken McCallum made the warning in an opinion piece published Friday to mark 25 years since the attacks.

What did MI5's chief say about the next major security shock?

MI5 Director General Ken McCallum wrote that security agencies must be ready to adapt to current and future threats rather than fixate on past ones.

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

Why does McCallum warn against preparing for past threats?

McCallum wrote that agencies "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." He added, "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 militants for mass casualty attacks, McCallum said. He pointed to a recently foiled Islamist plot to kill hundreds in gun attacks on the Jewish community in Manchester as evidence of that ongoing ambition.

What other threats is MI5 tracking beyond terrorism?

McCallum said MI5 is also facing rising state-backed aggression, ranging from sabotage carried out by criminal proxies to cyberattacks on power stations. Unlike in 2001, many systems and services are now in private hands, meaning governments, businesses and academia must work 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.

He closed the piece by saying, "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."