MI5 is devoting more resources to countering state threats than during the Cold War, its head, Sir Ken McCallum, said in London, describing Russia as “aggressor number one.” Threats from foreign adversaries had quadrupled, he said, and MI5’s operational missions against terrorism and state threats were “pretty much of equal scale.” It’s a striking shift.
McCallum delivered the figures and assessments in his annual speech at the domestic intelligence service’s headquarters. He warned of rising threats from Russia and Iran, alongside “extreme right-wing terrorism.” His remarks described the scale of the work facing the UK’s security service and the range of foreign and domestic threats it handles.
State Threats and Foreign Powers
McCallum said Russia was waging hybrid warfare while seeking to avoid a joint response from Nato. The Kremlin would be “foolish to cross” that line, he said. Russia had stopped short of “conventional conflict” with the military alliance and was trying to unsettle European countries. He described its progress in the full-scale invasion of Ukraine as “minimal and horrifically costly.”
MI5’s identification and expulsion of Russian spies from the UK has left the Kremlin relying on paid proxies for attempted attacks, McCallum said. “With its traditional covert footprint eviscerated by almost 1,000 expulsions since the invasion, the Kremlin’s global toolkit is weak. So we see them scrambling to pay criminals to do their bidding,” he said. “These are not the actions of a great power with the strategic upper hand.”
Iran was expanding a hybrid campaign in the UK, according to McCallum. Authorities made fifty arrests in the last year over Iran-linked activities. Much of the aggression had targeted Jewish communities, he said, as well as “harder targets, like military sites.” They’re facing a broad threat.
The National Security Act, enacted in 2023 to target people working against UK interests for foreign powers, is in heavy use, McCallum said. He said the law had been employed to tackle threats from China, Iran and Russia. It’s one of the tools used to address foreign activity in the UK.
Terrorism and Emerging Risks
McCallum said terrorism and state-threat operations were now of roughly equal scale within MI5. Islamist groups such as Al Qaeda and so-called Islamic State continued to direct and inspire attacks, he said. In April, the UK’s terrorism threat level rose to severe for the first time in five years, meaning an attack was highly likely.
The increased risk was driven “in significant part” by extreme right-wing terrorism, McCallum said. “Over the last year the most marked trend has been an increase in cases where extremist versions of anti-immigration and anti-Muslim grievance are tipping into terrorist intent,” he said. This form of terrorism tended to “skew young” and was driven by the internet.
MI5 recently investigated a “radicalised extreme right-wing 13-year-old here in the UK,” McCallum said. The investigation generated insight that enabled one of the service’s international partners to prevent a lethal attack on its soil. That’s what the work can do.
McCallum also said MI5 had caught terrorists seeking to use artificial intelligence to improve reconnaissance and attack methods, including by integrating the technology with drones. His greatest concern was extremist groups using AI to make bioweapons. The threat was “not yet realised,” he said, but the technology had the “potential to change the stakes on existing or even new bioweapons.” We can't ignore that risk.
He said the UK Intelligence Community—MI5, GCHQ and M16—was working with the UK’s AI Security Institute to address those risks. McCallum warned that the UK must stay ahead of the danger posed by violent groups developing new bioweapons.