Britain's domestic counter-intelligence agency is reportedly on 'high alert' amid the fears of Russian agents set to infiltrate the UK.
Threats include 'deniable' infrastructure attacks and operations to humiliate the UK government in an effort swing public opinion against Britain's support for Ukraine.
'There is a serious concern that officers or agents attached to Russia’s security services may attempt to enter the UK and target strategic locations,' a security source said.
Vladimir Putin has reportedly ordered intelligence officials to sabotage key UK infrastructure
Special Branch cops will now increase the monitoring of travellers to the UK, the source told The Sunday Express.
Putin's FSB security agency, formerly known as the KGB, is clamouring to restore its reputation amid repeated intelligence failures in Ukraine.
One of its most important officers is thought to have been locked up at Moscow's most notorious prison as Putin raged about a flurry of unexpected challenges.