If anybody was under any illusions about the level of threat posed by Russia to the UK, the Defence Secretary sought to shatter those this morning. In the minutes before John Healey entered the briefing room in 9 Downing Street, journalists wondered about what lay behind the hastily arranged press conference.

For those expecting an update on the fragile ceasefire between the US and Iran or the imminent future of the Strait of Hormuz, a map of the arctic indicated that was not the purpose of the briefing. Mr Healey is not a natural media communicator. He is competent, no doubt, but evidently he is more comfortable behind closed doors away from the media spotlight. Despite this, it was clear that the Defence Secretary believed that the deployment of the Royal Navy to track and deter a covert Russian operation ordered by Vladimir Putin, to survey underwater infrastructure, was a significant escalation by Moscow.

Mr Healey reiterated that despite war in the Middle East, Russia remains the greatest military threat to the UK and NATO after confirming that he had ordered the deployment of a warship alongside RAF P8 submarine-hunter aircraft in the high north.

The Defence Secretary said the operation to protect undersea cables amid Russian aggression had lasted “over a month” as critics allege the announcement sought to distract from errors made in response to the war in Iran.

The operation, which saw the UK work alongside allies, was launched “in the last few weeks” and saw an Akula attack submarine launched as a diversion to allow other Russian undersea naval units from the Main Directorate of Deep Sea Research (known as GUGI) to conduct “nefarious activity over critical undersea infrastructure.”

Mr Healey told reporters: “The Akula Submarine subsequently retreated home having been closely tracked throughout and we continued to monitor the two GUGI submarines, in and around wider UK waters.

“Our Armed Forces left them with no doubt that they were being monitored, that their movements were not covert as President Putin planned and that their attempted secret operations had been exposed.”

In a message directly to the Russian leader, Mr Healey added: “I say this: we see you, we see your activity over our underwater infrastructure. You should know that any attempt to damage it will not be tolerated and would have serious consequences.”

There is currently no evidence to suggest that any damage was inflicted on underwater cables which supply half of the UK’s gas supplies, 99% of international telecoms and trillions of pounds of global trade each day.

The Government and Royal Navy was widely criticised for its response to the crisis in the Middle East, with HMS Dragon not leaving port for 10 days after it was ordered to set sail for the eastern Mediterranean following an Iranian-backed drone attack.

Mr Healey was also condemned for the decision to remove the only mine hunting capability in the region just days before the US launched military action that resulted in the closure of the Strait of Hormuz.

Former Royal Navy officer and UK defence attache to Russia, John Foreman believes the press conference was an attempt to “justify Government inaction” in the Strait of Hormuz.

He told the Daily Express: “This is a long-term pattern of Russian behaviour and we need to be better prepared for it and it doesn't strike me that the left hand is talking to the right.”

He added: “I think really what this was about was John Healey and the Government trying to justify why they’re not doing anything by sending ships to the Gulf.

“By saying that Russia is so important that we can’t spare the ships. But actually that’s one frigate, we are meant to have 30 other frigates available, broadly.”

The announcement comes as the MOD confirmed that they had seen “increased Russian activity” in the Atlantic north of the UK, as attention was focussed on the crisis in the Middle East.

Former Navy submarine captain Ryan Ramsey believes the launch of submarines by Russia and the Royal Navy’s response could prove to be “a watershed moment” for senior planners.

He said: “I think they’ve realised that we’ve let our capability wane and it’s going to take us ages to regain that capability, unless the MoD starts to think innovatively.”

“I don’t think we are [prepared] but what the Navy is very good at doing is adapting very quickly, so I think this will refocus people on what’s really important to us, which is protection of the United Kingdom.

GUGI is Russia’s long-running military programme to develop capabilities to be deployed from specialist surface vessels and submarines, that are intended to survey underwater infrastructure during peacetime, but then damage or destroy infrastructure during a conflict.

British defences were previously tested by GUGI when the Russian spy ship Yantar sailed near UK waters last year. The ship was tracked by a Royal Navy frigate and RAF P8s, with lasers being directed at British pilots.

The Yantar is one the key vessels used by Russia to threaten the UK and our allies. Over the last two years, the UK has seen a 30% increase in Russian vessels threatening UK waters.

Mr Healey was also asked why the UK was letting Russia-flagged vessels pass through the Channel despite having announced British armed forces could begin seizing shadow fleet tankers in British waters.

The Defence Secretary said Moscow “still poses a threat and we will continue to do what we’ve done as a matter of course, which is ensure that we can escort any Russian warships through our waters and, in the case of this operation, to ensure that we can track any potentially malign activity, and that we can monitor and make clear that we have exposed any covert operations that Putin wants to mount that may threaten our vital interests”.