Reciprocal military deployments and exercises between NATO and Russia are upping the ante.
A total of 8,000 NATO soldiers have been deployed to the Finnmark region of northern Norway, 160-300 kilometres from the Russian border.
The move follows a series of joint military exercises that have been conducted by the Western bloc in response to the largest build up in the Arctic since the Cold War. Russia has built two military bases in the region – and has four more on the way.
The NATO deployment is intended to allay anxiety in Baltic and Scandinavian nations as to Russian expansionism. But why is NATO taking the build-up so seriously?
Why is the Arctic important?
The Arctic holds around 22 percent of the world's undiscovered oil and gas reserves, according to a report issued in 2008 by the US Geological Survey.
If Russia is able to tap into these reserves, the Russian economy would be able to survive Western sanctions. It would also increase Russian influence in the region.
Who governs the Arctic?
The United States, Russia, Canada, Norway and Denmark have territory bordering the Arctic.
Administration in the region is carried out according to laws and regulations of each individual Arctic state. But it can also be subject to bilateral, regional and international agreements.
According to the United Nations Convention on the Law of the Sea (UNCLOS), twelve miles offshore in the Arctic Ocean is territorial sea boundary, and anywhere from 200 to 350 miles offshore is defined as the exclusive economic zone (EEZ).
However, territorial disputes still continue – the most intractable is that of the Northwest Passage, a route connecting the northern Atlantic and Pacific Oceans through the Arctic Ocean.
The US and other nations assert that the passage is an international strait and subject to free navigation rights. Canada, however, claims that it's an inland waterway over which it has exclusive jurisdiction.
What is Russia's claim?
In 2015, Russia submitted a claim to the UN that it has a right to 500,000 square miles of Arctic ice surface, including the North Pole, parts of which have already been claimed by Denmark.
Its previous claim was rejected in 2002 by a UN commission on the grounds of insufficient evidence.
In 2007, Russia planted a titanium flag 4.267 metres below the polar ice in the Arctic Ocean which was interpreted as a symbolic claim to the Arctic.
What is Russia doing to worry the West?
The territorial disputes are nothing new. But the tensions have never been so high.
"We're seeing activity that we didn't even see when it was the Soviet Union. It's precedential activity," US Navy Admiral Michelle Howard said.
Western countries have been alarmed over the last two years as Russia, under President Vladimir Putin, began to reopen military, air and radar bases on archipelagos above the Arctic Circle that were closed at the end of the Cold War.
Russia has built two new military bases in the Arctic so far and is constructing four others at Rogachevo, Cape Schmidt, Wrangel and Sredniy.
In 2013, Putin announced Kremlin plans to bolster the country's naval presence in the Arctic, sparking fears that the country could attempt a military-led land grab.
Russia is building three nuclear icebreakers, including the world's largest, Arktika.
Russia is expected to commission the lead ship of its new class of nuclear-powered icebreakers in 2019, said Vyacheslav V Ruksha, the head of Atomflot, Russia's state-owned company that maintains the world's only fleet of nuclear-powered icebreakers.
"The Arktika will be the flagship in the Russian nuclear icebreaker fleet," Ruksha said.
Russia already has the biggest nuclear fleet in the world. But its fleet, which has around 40 breakers including six nuclear ones, will be strengthened further after Arktika.
No other country has a nuclear breaker fleet, used to clear channels for military and civilian ships.
"Under [Soviet leader Mikhail] Gorbachev and [Russian President Boris] Yeltsin, our Arctic border areas were stripped bare," said Professor Pavel Makarevich, a member of the Russian Geographical Society.
"Now they are being restored."
How is NATO reacting?
NATO has deployed heavy arm equipment and troops in northern, central and eastern Europe to deter Moscow's aggression in the region.
Poland hosted around 3,500 US soldiers last January. This was one of the largest deployments of US forces in Europe since the Cold War.
A UK-led battalion and 800 troops from Denmark and France are now settled in Estonia.
Another 1,200 troops from a Canadian-led battalion are stationed in Latvia, while Lithuania hosts 1,200 troops in a German-led battalion.
Norway has also been hosting around 300 US marine troops for six months, for the first time since the Second World War.
According to a report released by NATO last March, defence spending by European allied states inched up for the first time in seven years in 2016.
"The US Navy is likely to grow, so there may be a greater subsurface (submarine) presence in the region, but not markedly," Professor James Kraska of the US Naval War College said.
Rob Huebert, who is an associate professor at the University of Calgary, says militarisation in the Arctic is definitely an issue and it depends on the US' isolationism in the region where "the US already has a hefty military presence."
Huebert says currently the US holds the largest submarine attack fleet which is difficult to get information about "because it is so secret."
What can we expect from the Trump administration?
Washington is closely watching the developments.
It is "not to our advantage to leave any part of the world," US Defense Secretary James Mattis said when he was asked about Russia's military build-up in the Arctic.
US President Donald Trump signed an executive order last week to extend offshore oil and gas drilling to areas that have been off-limits in order to boost domestic production.
Trump's order reverses former President Barack Obama's decision to place certain parts of the Arctic permanently off-limits to drilling.
Obama had banned new oil and gas drilling in federal waters in the Atlantic and Arctic oceans, protecting 115 million acres of waters off Alaska and 3.8 million acres in the Atlantic.