MI5 chief Ken McCallum also said China poses "the most game-changing strategic challenge to the UK."
London CNN  — 

Russia’s ability to spy in Europe has been dealt the “most significant strategic blow” in recent history after coordinated expulsions of diplomats since the invasion of Ukraine, with a hundred diplomatic visa requests refused in the UK alone in recent years, according to the head of the UK’s security services, MI5.

Ken McCallum, the director general of MI5, said in an annual speech outlining threats to the United Kingdom that this year 600 Russians officials had been expelled from Europe, 400 of whom his agency judged to be spies.

“We’ve continued to work intensively to make the UK the hardest possible operating environment for Russian covert action,” said McCallum. “In the UK’s case, since our removal for 23 Russian spies posing as diplomats, we have refused on national security grounds over 100 diplomatic visa applications … the serious point is that the UK must be ready for Russian aggression for years to come.”

In comments after the speech, McCallum called the expulsions “a very, very large dent in the Russians call about positioning across Europe,” adding data about agents was shared between European allies so that “it’s not easy for the Russians to cross post” one spy “expelled from country A to Country D.”

He added: “I hope what will continue to be true is that a very large volume of trained, experienced Russian intelligence talent, if I can use that term, will be of far less utility and most other parts of the world for many years to come.”

The speech also revealed a growing threat of Iranian state foul play including “ambitions to kidnap or kill British or UK-based individuals perceived as enemies of the regime”, said McCallum. He revealed there have been 10 “such potential threats since January alone in the UK”.

In the later comments, he added that Iran a was “prepared to take reckless action,” and characterized them as a “sophisticated adversary.” He said: “They have sometimes operated using their own operatives doing things with their own hands. And on other occasions, they have co-opted other people to work on their behalf.”

McCallum said that terrorism remained an enduring threat and that eight “potentially deadly plots” had been stopped in the last year. He assessed that three-quarters of them related to Islamist extremism, and a quarter to extreme right-wing terrorism. He added the latter extremism was increasingly luring in younger Britons, with the “youngest case I think I can recall, horribly … where the individual potentially causing some threat was 13 years old.” He declined to provide details.

Among state actors, China poses “the most game-changing strategic challenge to the UK,” he said. “We see Chinese authorities playing the long-game in cultivating contacts to manipulate opinion in China’s favour – seeking to co-opt and influence not just prominent parliamentarians across the political landscape, but people much easier in their careers in public life, gradually building a debt of obligation.”