There is a “real and present danger” that Vladimir Putin will launch a campaign of undercover attacks to destabilise the Baltic states on Nato’s eastern flank, the Defence Secretary has warned.

Michael Fallon said the Russian president may try to test Nato’s resolve with the same Kremlin-backed subversion used in Crimea and eastern Ukraine.

A murky campaign of infiltration, propaganda, undercover forces and cyber attack such as that used in the early stages of the Ukraine conflict could be used to inflame ethnic tensions in Estonia, Lithuania or Latvia, he said.

The military alliance must be prepared to repel Russian aggression “whatever form it takes”, Mr Fallon said, as he warned that tensions between the two were “warming up….”

The former Soviet states of Latvia, Lithuania and Estonia could be next to face a Russian-backed campaign to destabilise them, Mr Fallon warned….

Mr Fallon said: “It’s a very real and present danger. He was testing Nato all last year, if you look at the number of flights and the maritime activity.

“He flew two Russian bombers down the English Channel two weeks ago. We had to scramble jets very quickly to see them off. It’s the first time since the height of the Cold War, it’s the first time that’s happened.”

“That just shows you, you need to respond, each time he [Mr Putin] does something like that, you need to be ready to respond.”

A sharp increase in Russian defence spending is “clearly worrying”, he added.

“They are modernising their conventional forces, they are modernising their nuclear forces and they are testing Nato, so we need to respond.”

Image: British Defense Minister Michael Fallon, Aug. 16, 2014 (photo: UK Ministry of Defense