The UK spy chief claims that Russia is on a "continued effort" to cause chaos in Europe's streets.

• The most complex threat environment we have ever seen is the ongoing efforts by autocratic states to harm Britain's security, as stated by MI5 director Ken McCallum in a rare public speech.
• The spy chief stated that the agency was grappling with a diverse array of beliefs and ideologies, including those posed by Russia, Iran, and China, among others.
• Since the start of Russia's full-scale invasion of Ukraine in early 2022, more than 750 Russian diplomats have been expelled from Europe, with the majority of them being spies, according to McCallum.

On Tuesday, the head of Britain's domestic spy agency accused Russian military intelligence of being on a "continuous campaign" to cause chaos in Britain and Europe.

The most complex threat environment we have ever seen is the ongoing efforts by autocratic states to harm Britain's security, as stated by MI5 Director General Ken McCallum in a rare public speech from MI5's counter-terrorism operations center in London.

Since 2017, MI5 and police have thwarted a total of 43 late-stage attack plots, with some plotters aiming to acquire firearms and explosives in the final stages of planning mass murder.

The spy chief stated that the agency was grappling with a diverse array of beliefs and ideologies, including those posed by Russia, Iran, and China.

The number of state threat investigations MI5 is conducting has increased by 48% in the past year, according to McCallum.

McCallum stated that the U.K.'s prominent role in backing Ukraine makes us a significant figure in Putin's regime's thoughts, and we should anticipate further hostile actions on our own soil.

The Russian military intelligence, GRU, has been on a mission to cause chaos on British and European streets, as evidenced by arson, sabotage, and other acts of mayhem.

No representative from Russia's foreign ministry responded to CNBC's request for comment on Tuesday.

Since the start of Russia's full-scale invasion of Ukraine in early 2022, more than 750 Russian diplomats have been expelled from Europe, with the majority of them being spies, according to McCallum.

He stated that the current situation surpasses all historical precedents and has significantly hindered the Russian intelligence services' capacity to inflict harm in the West.