During an annual threat update on Tuesday, the head of Britain’s domestic intelligence agency, Ken McCallum, addressed long-standing questions regarding Russian involvement in the 2016 Brexit referendum. McCallum confirmed that Russia utilized social media platforms and state-backed television outlets to attempt to influence public opinion during the campaign period. Specifically, he noted that the Russian-owned broadcasters RT and Sputnik increased their output significantly around the time of the vote.

Despite confirming these interference efforts, McCallum explicitly stated that there is no evidence to suggest the Kremlin’s actions had a measurable impact on the referendum result. He expressed concern that the ongoing political debate surrounding this interference has inadvertently provided the Kremlin with a "propaganda victory" by amplifying the perception of Russian reach. McCallum’s comments served to endorse recent statements made by Andy Burnham, who had raised the issue of foreign interference in the days leading up to the briefing. While the intelligence chief acknowledged the reality of the interference, he urged a shift in focus, suggesting that the continued public debate over the referendum's integrity may be counterproductive to national security interests.