Putin in a submarine
Russia's Prime Minister Vladimir Putin (L) waves onboard of 'Mir-2' mini-submersible Getty

The RAF are scouring the Scottish coast for a Russian submarine that may have been spotted in the area. An RAF plane, as well as a Royal Navy frigate, HMS Sutherland, and a hunter killer submarine are "conducting activity" in the North Sea according to the Ministry of Defence.

Canadian and French maritime patrol aircrafts are also involved with the search - the third time this year that Britain has called on its allies to search for a Russian submarine in the area. Moscow has stepped up undersea patrols with fears they could be trying to spy on a Trident nuclear deterrent sub.

There is growing concern among US military and intelligence officials that Russia could attempt to sever underwater fibre-optic cables upon which governments, economies and citizens depend. Pentagon officials are focusing significant attention on the movements of Russian spy ships and submarines near cable routes that carry electronic communications.

A French Atlantique 2 maritime patrol plane has been conducting searches as the RAF currently has no maritime patrol aircraft of its own. The Telegraph reports the French plane has searched for the submarine for at least 10 days in waters north of Scotland.

The Ministry of Defence did not confirm it was looking for a foreign submarine. They said: "We can confirm that allied maritime patrol aircraft based at RAF Lossiemouth for a limited period are conducting activity with the Royal Navy. We do not discuss the detail of maritime operations."

Predictably, details of Russia's naval activities are classified, however reports revealed suspicious activity has been monitored in the North Sea, north east Asia and close to US shores. Some officials have gone as far as to call the level of Russian activity as "comparable to what we saw in the Cold War".

"The risk here is that any country could cause damage to the system and do it in a way that is completely covert, without having a warship with a cable-cutting equipment right in the area," said Michael Sechrist, a former project manager for a Harvard-M.I.T. research project funded in part by the Defense Department, as reported by the New York Times.

In January, members of an alleged Russian spy ring were detained in Šiauliai, Lithuania, near a Nato airbase after being suspected of infiltrating the Lithuanian army. The accused spies were captured on near Nato's Zoknai air base: a facility that offers protection to Estonia, Latvia and Lithuania.