MI5 chief confirms Russian interference in Brexit referendum
Ken McCallum says vote was not swayed and Moscow gains from the debate, threat speech launches AI bioweapons centre
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Ken McCallum giving a speech today. Photograph: Jonathan Brady/Pool PA/AP
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Director general of MI5 Sir Ken McCallum gave a speech at Thames House in London on Tuesday (PA Wire)
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US Bombers Depart RAF Fairford For Home after suspected plot against the airbase in Gloucestershire (Getty)
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Sir Ken announced the launch of a new AI Threat Assessment Centre (Jonathan Brady/PA)
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Seven people were arrested and bailed by counter-terrorism police after the RAF Fairford incident (PA)
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Ann Widdecombe speaking during a Reform rally (Lucy North/PA)
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MI5 chief Ken McCallum confirmed on Tuesday that Russia attempted to interfere in the 2016 Brexit referendum, and said no evidence suggests the effort swayed the result.
The interference ran through anti-EU coverage on the Russian-backed outlets RT and Sputnik, and through a second line of troll social media accounts, McCallum said in his annual threat speech at Thames House. He drew what he called a big difference between "what may have been attempted and what actually resulted," said the effort is generally believed to have been marginal, and put no new evidence into the public domain.
He went further than confirming the attempt. It would be to Russia's benefit if the issue was talked about further, he said, and he was "a little bit worried" that the trolls "who didn't appear to do all that much" would be delighted to find themselves front-page news again. "It is up to us how far we allow our adversaries to divide us." Andy Burnham had raised the decade-old interference attempts in remarks over the weekend, and backed off after the Conservatives challenged him on whether that meant he regarded the Brexit vote as illegitimate.
The same speech introduced the next threat category. Terrorists have been caught seeking to use artificial intelligence to improve reconnaissance and attack methods; AI-enabled drones add "a new twist"; the greatest concern is "AI's potential to change the stakes on existing or even new bioweapons." Al Qaida around 9/11 would dearly have loved a chemical or biological capability, McCallum noted, and it has not been easy for anyone to achieve — but comparatively low-sophistication actors could gain one if guardrails fail to function as intended. MI5 announced a new AI Threat Assessment Centre, with the intelligence community — MI5, GCHQ and MI6 — working alongside the UK's AI Security Institute, and McCallum called for a "whole-of-society effort" against threats that could disrupt banking, flights and hospital treatment.
The resource numbers point one way. The state threats caseload has quadrupled in ten years, and in 2026 MI5 devotes more resource to countering state threats than it did during the Cold War. Russia remains "aggressor number one," its authorities scrambling to pay criminals or exploit naive volunteers while their military progress in Ukraine is, in McCallum's words, "minimal and horrifically costly." More than fifty arrests have been made in Iran-linked operations in Britain over the past twelve months, with Tehran principally hiring criminals to do its bidding. Almost a thousand Russian representatives have been ejected from allied countries since the full-scale invasion of Ukraine.
The referendum interference took a decade to be declared marginal. The AI threat, which McCallum acknowledged has not yet been realised, already has its own assessment centre.