MI5 chief McCallum warns Britain enters new era of Iran and Russia threats

MI5 Director General Ken McCallum said on 13 October 2026 that Britain and Europe had entered a new era of national security, warning of escalating threats from Iran and Russia. Speaking at MI5's Thames House headquarters in London, McCallum delivered his annual threat update and said Iran is increasingly targeting British military sites, expanding beyond its previous focus on dissidents and Jewish sites.upi.com+1

What the annual threat update said

McCallum said Iran has attempted to expand a hybrid campaign using criminal proxies to intimidate oppositionists, Iranian media organisations and Israeli sites. He said much of this aggression has been aimed at British Jewish communities. He warned that a major shift this year has been Iranian ambitions to come at harder targets, like military sites, moving beyond the softer targets Iran previously pursued.

Over the past year, intelligence operations led to more than 50 Iran-linked arrests in Britain, McCallum said. He referenced an incident on 27 September 2026 at RAF Fairford, a military base in rural England from which the US had launched bombers in an assault against Iran. McCallum declined to give details, citing ongoing investigations, but said the case was not unique.

In the early hours of 27 September 2026, a member of the public called police after spotting three vans in a country lane near RAF Fairford. Seven men in their 20s, one a dual British-Irish national, were arrested and released on bail. Authorities said they found only gasoline in the vehicles. A week later, the US withdrew its bombers from the base after reports of a possible drone attack.

Where the arrests and incidents occurred

Prime Minister Andy Burnham told Parliament on 12 October 2026 that the Fairford incident was highly likely to have been coordinated in Iran and almost certainly directed by Iran's Islamic Revolutionary Guard Corps. Foreign Secretary Ed Miliband summoned Iran's ambassador and sanctioned Ruhollah Bazghandi, head of counterespionage operations in the IRGC, and Shahram Ali Reza Tamarzadeh Jakki, an alleged facilitator for the Zindashti criminal network.

McCallum said Iran has so far been hiring unsophisticated criminals for operations in the UK, limiting its ability to carry out complex attacks using explosive drones, but warned that could change. On Russia, he said its military and intelligence services are escalating hybrid warfare attempts while trying not to trigger NATO's Article 5 threshold, under which allies would be expected to defend one another.

McCallum said MI5 remains focused on efforts by the Chinese government to conduct espionage, coercion or democratic interference, and on attempts by Al Qaeda and ISIS to carry out mass-casualty attacks. He also warned that artificial intelligence could be used by terrorist groups to create new bioweapons, and that MI5 has formed a new centre focused on threats from AI advances.

What happens next

McCallum warned that beyond misuse of AI by human adversaries sit potential risks posed by AI itself, saying human history has given no experience of facing an actor smarter than humans. He said many terrorists would dearly love to have some kind of capability with biological, chemical or radiological weaponry, and that there is a risk AI could generate novel pathogens not previously seen.

Iran has denied any connection to plots on British soil. McCallum warned of an unflinching response to those who seek to cause mayhem on British streets, whether hired thugs or their paymasters overseas. Burnham said Britain will crack down on Iran's use of criminal networks and bring further sanctions to restrict the capacity of Iran and the IRGC.