MI5 says Iran is pursuing harder UK targets as Russian hybrid activity grows

Iran is attempting to reach harder targets in Britain, including military sites, while Russia is escalating hybrid activity against Ukraine's allies, MI5 Director General Ken McCallum said in his annual threat update. He described Russia as Britain's leading state-based aggressor and said MI5 now devotes more resources to state threats than during the Cold War.

McCallum said more than 50 arrests connected to Iranian activity had been made in the previous year. He cited a suspected plot involving RAF Fairford as evidence of higher ambition, while stressing that Iran's operational capacity in Britain remains limited. Tehran and Moscow deny British accusations that they direct hostile operations in the country.

The MI5 chief also announced an AI Threat Assessment Centre. He said the most serious prospective danger was advanced systems helping terrorists or hostile states acquire knowledge needed for chemical or biological weapons, including novel pathogens. That was a warning about capability and access, not a claim that such an attack had occurred.

Google Trends showed UK searches for MI5 and Ken McCallum rising during the preceding four hours. The trend is a measure of regional attention, not proof of the intelligence assessment; the underlying claims come from McCallum's published speech and independent reporting.