McCallum has been an intelligence officer at MI5 for over two decades, including service focused on
Northern Ireland-related
terrorism and leading
counter-terrorism investigations during the
London 2012 Olympic Games. In 2018, McCallum took charge of the MI5 response to the attempted assassination of
Sergei Skripal.
Director General of MI5 In April 2020, McCallum succeeded
Sir Andrew Parker as
Director General of MI5. In 2021, McCallum said in his annual threat update that the activities of China, Russia, and other hostile states could have as large an impact on the public as terrorism, marking a significant shift in emphasis for the UK's domestic spy agency. McCallum said that the British public will have to "build the same public awareness and resilience to state threats that we have done over the years on terrorism". At a joint press conference with
Christopher A. Wray in July 2022, McCallum said that MI5 had "more than doubled" its effort against Chinese activity over the same timeframe as part of an unprecedented joint warning with his counterpart at the FBI. He added the "most game-changing challenge" MI5 faced came from an "increasingly authoritarian Chinese Communist party". In November 2022, McCallum said there had been at least 10 potential threats by Iran to kidnap or kill British or UK-based people in 2022. McCallum also warned that the UK "must be ready for Russian aggression for years to come". In 2023, he noted the increased risks to the UK during the Israel–Gaza war. "One of the things that concerns me most right now, is to understand quite what the shape of the UK impact will be", McCallum said in an interview. He also warned there was a risk that events in the Middle East could radicalise people towards violence. In October 2023 McCallum stated that more than 20,000 people in the UK were approached covertly online by Chinese spies. It comes amid a new warning to tens of thousands of British businesses of the risk of having their innovation stolen. He stated, "We have seen a sustained campaign on a pretty epic scale", McCallum told the BBC in an interview. In a 2024 speech, he stated that Russia's intelligence agency has been on a mission to generate "mayhem on British and European streets". He warned the UK faces the most "complex and interconnected" threat it has ever seen. He added there had been 20 Iran-backed plots since 2022. In a December 2024 podcast interview with
Simon Case, McCallum stated that MI5 has had to "pare back" its counter-terrorism focus due to the growing threat from Russia and other hostile states. Highlighting finite resources, he stated, "we had the 20- to 30-year holiday from that kind of big player, sophisticated states in serious conflict with each other. It's back, I'm afraid". In the same podcast, McCallum spoke about the adjustment needed as the public head of MI5, "Having spent all of my career being the world's most boring neighbour at barbecues, on the street, and being as deflective and uninteresting as you can possibly be, [it is] quite odd to then be on the telly. Even some members of my own extended family were completely shocked", he says. On 15 October 2025, after the collapse of a case concerning allegations of Chinese spying, McCallum stated MI5 had intervened operationally to disrupt Chinese activity of national security concern in the past week. McCallum said that it was "frustrating when prosecutions fall through". ==References==