A major military effort by Russia has been launched to build up its strength in the Arctic circle. Journalists were invited to the Alakurtti base, which is 250 miles from the northern port of Murmansk and on the country's border with Finland.

During the era of the Soviet Union, large numbers of forces were deployed to the Arctic Circle to enhance its strategic defences. The peninsula the base is located on was called the "unsinkable aircraft-carrier" due to a large number of airbases there, according to ABC News.

Russia is now again increasing its presence in the Arctic, with a number of new bases and renovating disused Soviet buildings. An air defence shield will be constructed, covering most of the northern coast and a communications infrastructure is also being created along the northern coast.

As ice recedes in the Arctic, natural resources are being uncovered, with new shipping and transportation routes. The US Geological Survey estimated that 13% of the world's undiscovered oil and 30% of its gas lie untapped there.

"For the scale of what Russia is doing, it's hard to find a comparison in any of the other Arctic states," said Katarzyna Zysk, from the University of Oxford and a professor at the Norwegian Institute for Defence Studies who studies Russian military policy in the Arctic.

In March, President Vladimir Putin visited a new facility called the "Northern Shamrock" which can accommodate 150 personnel and also host air defence units.

A new "Arctic Brigade" has been established at Alakurtti and two more bases are planned. A claim was submitted to the United Nations that 460,000 square miles of ocean floor in the Arctic should be considered as belonging to Russia.

Russian military planners view the Arctic as a vulnerable area in the event of a conflict with the US and Nato.

"In general there are good reasons to think that this investment Russian is making in the Arctic is irrational," Professor Zysk said. "Everyone thinks that the Arctic is the last place that Russia should invest. And still Russia is doing it. I think it's genuinely important for the Russian authorities."