He said: “We have long been aware of the West’s plans for Kaliningrad.

“The Kaliningrad region is an integral part of Russia, and any military encroachment on it will be met with an immediate and crushing response using all the forces and means at our disposal.”

Patrushev, a former head of the FSB counterintelligence service, warned: “Russia has all the necessary military instruments to guarantee the security of the Kaliningrad region,” as he specified that he was discussing a nuclear response.

It comes as Polish Prime Minister Donald Tusk concurred with the assessment of a senior US General that Russian forces could be ready for a confrontation with Europe within 18 months.

General Alexus Grynkewich, the newly appointed NATO commander in Europe, said US intelligence assessments suggested that Russia could achieve operational readiness for a European conflict within the next two years.

He warned: “If Xi Jinping decides to launch military action against Taiwan, it is likely he will coordinate it with Vladimir Putin, which creates the potential for a global conflict.”

Tusk addressed the general’s comments and said: “Today, NATO’s Supreme Allied Commander in Europe, General Alexus Grynkewich, confirmed to me the American assessments that Russia will be ready for confrontation in just a year and a half.

“Russia will be ready for confrontation with Europe — and therefore with us — as early as 2027.”

Following meetings with the outgoing and incoming head of MI6, he added in a statement: “All of these meetings and decisions are dedicated to one thing: Poland must be ready. The Polish Armed Forces must be well-equipped. The situation inside Poland must remain stable so we are prepared for any scenario.”