Russia is now waging hybrid warfare – MI5 chief
MI5 is devoting more resource to countering state threats than during the Cold War, the head of the intelligence service has said.
Delivering his annual threat update, Sir Ken McCallum said threats from foreign adversaries had quadrupled in the last decade, with Russia "aggressor number one".
This threat is coupled with increased Iran-linked aggression against Jewish sites and military bases.
McCallum said Russia was waging hybrid warfare at a time when AI was "supercharging the cyber-security contest between attackers and defenders".
He urged the British public to play a greater role in protecting the country.
National resilience has become a third core MI5 mission, alongside counterterrorism and countering state threats, he said.
He identified three priorities:
- Protecting critical infrastructure,
- Strengthening societal cohesion, and
- Addressing emerging technological risks.
Energy networks, financial systems, water supplies and healthcare services remain vulnerable to cyber-attacks and sabotage, he added.
The speech also warned that hostile actors are exploiting social divisions, spreading disinformation and targeting democratic institutions, religious groups and political figures.
Radicalised 13-year-old
MI5 has investigated a radicalised 13-year-old in Britain, he said:
“Believe me, we wish we didn’t have to. But that investigation generated insight that enabled one of our international partners to prevent a lethal attack on their soil.
“Similarly, a 16-year-old from Inverclyde recently received a ten-year prison sentence for his failed attempt to mount an attack against his local Islamic Centre,” the MI5 chief said.
The director highlighted the potential misuse of AI to develop biological weapons as a particularly serious future concern.
“You might be surprised to know that in 2026, MI5 is devoting more resource to countering state threats than during the Cold War.
“Over the last decade, our State Threats caseload has quadrupled,” he said.
The director said Russia increasingly relies on criminal networks and recruited individuals to conduct hostile activities, particularly following the expulsion of Russian intelligence officers from Western countries after the invasion of Ukraine.
Iran was also identified as a significant concern. The speech reported more than 50 arrests in Britain over the preceding 12 months linked to Iran-related operations.
Alleged plots and arson incidents targeting Jewish communities, synagogues and businesses were highlighted.
Counterintelligence priority
China remains a counterintelligence priority, particularly concerning espionage, political interference and attempts to access sensitive research.
The director urged universities and businesses to manage security risks while maintaining beneficial international partnerships.
Severe threat
Britain’s terrorism threat level has returned to severe, meaning an attack is considered highly likely, he said.
The director called on infrastructure operators, defence suppliers, researchers and technology companies to strengthen their security measures.
Parents concerned about online radicalisation were encouraged to seek professional support, while members of the public were urged to report suspicious activity through official channels.
Sir Ken said Russia had stopped short of "conventional conflict" against Nato and is instead trying to unsettle European countries while its progress in its full-scale invasion of Ukraine is "minimal and horrifically costly".