Russia remains the most significant state threat to European security, Britain's domestic intelligence chief warned on Tuesday, as Moscow steps up hybrid attacks across the continent while its military campaign in Ukraine stalls.
In his annual threat update delivered from MI5's headquarters at Thames House in London, Director General Ken McCallum said the agency was now dedicating more resources to countering state threats than at any point during the Cold War. He described Russia as "aggressor number one" and said its intelligence services were deliberately operating below the threshold that would trigger a NATO Article 5 response.
"The Russian military and intelligence services are once again escalating their attempts at hybrid warfare, being careful to stay below the NATO Article 5 threshold, which would be foolish for them to cross," McCallum told the audience.
His remarks come amid a wave of suspected Russian sabotage and interference across Europe. In August, Berlin blamed Moscow for a drone attack at Leipzig/Halle airport, while Tallinn accused Russian special services of ordering an arson attack targeting Estonian defence firm Milrem Robotics. These incidents, McCallum said, are part of a broader Kremlin strategy to "unsettle" European nations as it continues its full-scale war in Ukraine, now in its third year.
A weakened but dangerous adversary
McCallum noted that Russia's military progress in Ukraine has been "minimal and horrifically costly," which has pushed the Kremlin to turn to proxies to carry out attacks on European soil. "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.
The assessment aligns with recent warnings from NATO and EU officials about the growing threat of hybrid warfare. A proposal for a new European Security Council has been floated in Brussels to better coordinate responses to such challenges, and NATO has issued its own warnings as attacks escalate.
British Prime Minister Andy Burnham has reiterated the UK's unwavering support for Ukraine, vowing to continue backing Kyiv "100%" despite Russian threats of consequences. During a visit to Kyiv in August, Burnham stressed his government's "complete solidarity" with Ukraine and pledged to expand sanctions against Moscow.
McCallum also addressed Iran, calling it another state "keen on subcontracting its UK violence" and seeking to "expand" its hybrid campaign. He said Iran-linked operations had led to more than 50 arrests over the past year, with much of the aggression targeting British Jewish communities. However, he warned that Tehran was also looking to strike "harder targets, like military sites."
His comments follow a statement by Burnham to parliament that an incident at RAF Fairford, an airbase in Gloucestershire housing US Air Force personnel, was "almost certainly directed" by Iran's Islamic Revolutionary Guard Corps (IRGC). In late September, five men were arrested near the base on suspicion of explosives offences, later released on police bail. Two further arrests were made in London in October, including a dual UK-Iranian national and a British man, both on suspicion of preparing terrorist acts.
The warnings come as Russia continues to strike Ukraine's energy grid, despite diplomatic efforts to broker a ceasefire. McCallum's assessment underscores the persistent and evolving nature of state threats facing Europe, requiring vigilance and cooperation across the continent.
