Calls are being made for the defence of the Shetland Isles to be strengthened after increased sightings of Russian trawlers off the coast of Scotland.

Recent analysis by the Daily Telegraph also revealed that there have been more than 500 incidents where Russian boats have been stationed above undersea cables linking Britain with Europe and the US. These cables carry the majority of telecoms data abroad.

The growing importance of undersea infrastructure prompted a parliamentary report last year to warn of security vulnerabilities in areas including transport and supply chains, financial services and payment systems.

There are also concerns that the £30m SaxaVord Spaceport in Shetland could be a Russian target. But do the Shetland Isles really need better protection by the military? In recent years there have been a number of incidents in the Baltic Sea where underwater cables have been damaged or completely cut.

In December last year, Finnish police detained a vessel sailing from Russia, which was suspected of damaging an undersea telecoms cable running from Helsinki to Estonia, across the Gulf of Finland.

In 2022, Shetland was cut off from the mainland after a nearby subsea cable was damaged And last year there were two cable breaks in Shetland which disrupted internet services and, in one case, took weeks to repair.

There has been no suggestion that there was any Russian involvement in the Shetland incidents but they demonstrate how fragile the cables are and show the devastating effect on the islanders when they are damaged.

In July, Royal Navy warships and helicopters spent 21 days monitoring Russian activity in UK waters and the North Atlantic - this was a 25% increase on previous time spent monitoring.

The recent Telegraph revelation of more than 500 incidents where Russian boats have been stationed above undersea cables has also caused concern.

Jon Sandison, a high school history teacher and Shetland tour guide, said there were real concerns that Shetland could be attacked after Germany invaded Norway in 1940, during World War Two.

"Shetland could have been a stepping stone towards Orkney and mainland Scotland," he said.

There were many army, naval and RAF personnel stationed across the isles and coastal defences were built to defend Lerwick and the rest of the archipelago.

The SaxaVord Spaceport sits on a former RAF base and RAF Skaw played an important role in efforts to detect enemy aircraft from 1941.

RAF Saxa Vord was later involved in Nato's radar network to monitor Soviet activity during the Cold War.

The radar station closed in 2006 but it was revived in 2018 for Arctic surveillance as an automated remote radar head.

Sandison said that while military presence reduced in the second half of the 20th Century, Shetland's geographical position would never change.

"Where we are in the UK is always going to be a pivotal geographical location in relation to the North Sea, the Arctic Circle and wider scope of Britain," he said. He added that coastal infrastructure was built very quickly during the Second World War.

"Air raid shelters, anti-aircraft defences - it's remarkable how much was built in a short space of time," he added.

"Not much of the infrastructure remains.

It's part of our history, and part of our past." First Minister John Swinney has accused the UK government of leaving "Scotland's vast coastline dangerously exposed".

He pointed to waters off Shetland as an area of significant Russian activity.

"I don't think we've got nearly the presence in those areas that we require today," he told BBC Scotland News Liberal Democrat MP Alistair Carmichael, whose constituency covers Shetland, has urged the UK government to step up efforts to protect critical infrastructure.

He told the BBC's Radio Scotland Breakfast programme: "This is something we do need to be taking seriously.

"We're not expecting an imminent problem here but this is a time where the government is already telling us that we should all be keeping baked beans and a wind-up torch in a cupboard." Carmichael added that if the world had changed so much, some of the decisions made by the UK government to remove military presence from the northern isles may now need to be looked at again.

He said that over the last 20 years, there had been just one local full-time soldier running a reserved unit in Shetland but they were now managed from the Scottish mainland.

Carmichael said there should be restoration of a full-time presence to support the unit and more reserves should be recruited in the northern isles as numbers were low.

But he added: "If the signal that the government is sending the community is that we don't even think its important enough to send one full-time solider to run these units then you can't expect the community themselves to be particularly enthusiastic about it." SaxaVord in Unst is the UK's first fully-licensed spaceport with several companies interested in using the site to launch small satellites into orbit.

In September, the UK government announced investment of £30m in the project, as part of a new £7.8bn space strategy.

Alistair Carmichael said the spaceport would draw more attention to Shetland as a significant asset.

The German and UK governments plan to use SaxaVord to deepen their co-operation on space In October, Prime Minister Andy Burnham and Chancellor Friedrich Merz met in Berlin and announced plans to work more closely on economic growth, defence and technology. SaxaVord Spaceport was identified as a focus for immediate work on European launches. Two German companies are currently in a race to be the first to test a rocket in Shetland.

Chief executive Scott Hammond said: "The space strategy is absolutely critical. "We're at the heart of the UK government's plans for assured access to space.

"That's also for our economic and Nato partners." He added that the UK government had joined as one of its majority investors, with a member on the board, but stressed that SaxaVord Spaceport was still a private commercial company. A Ministry of Defence spokesperson said: "We are clear-eyed about the threat Russia poses.

"Through the UK-led Joint Expeditionary Force, we are leading allied activity across the High North, strengthening Nato's northern flank and increasing our ability to respond rapidly to emerging threats.

"This government is also investing in the capabilities needed to meet those threats, with £1.5bn backing Atlantic Bastion to deliver a next-generation Hybrid Navy and a further £330m to strengthen the protection of critical undersea infrastructure."