EVENES, Norway – During a frozen morning in Arctic Norway, a group of British and Norwegian soldiers padded softly through a snow-blanketed birch forest.
They were on a simulated NATO reconnaissance mission, among some 30,000 troops who took part in a drill rehearsing a counter-attack against an invading “enemy to the east,” a euphemism for Russia, Norway’s Arctic neighbour.
Russia has raced far ahead in Arctic defence over the past decade, modernising the world’s largest ice-breaking fleet as climate change creates new routes; and reopening dozens of Soviet-era bases in a region that provides the shortest path to the United States for its nuclear intercontinental missiles.
The exercises in March were part of a stepped-up effort called Arctic Sentry that aims to show Washington that Europe and Canada can defend the alliance’s northern flank.
Secretary-General Mark Rutte announced Arctic Sentry in February as he lobbied US President Donald Trump to drop a push to acquire Greenland.
Rutte was successful with Trump, but significantly strengthening the alliance’s Arctic posture is more challenging, interviews with dozens of current and former NATO officials and Arctic experts show.
It requires long-term investments in a wide range of assets – including ice-breakers, submarines, drones and satellites – testing allies’ economic and military resources at a time when Trump has threatened to leave NATO altogether and Washington is withdrawing troops, planes, ships and weapons from Europe.
Through most of NATO’s eight-decade history, the inhospitable High North was low priority.
But melting ice, Russia’s growing strength in a mineral-rich region larger than the United States and increased interest from China have changed that calculus.
“No major power in the 21st century will be able to maintain its position on the global scene without, in one way or another, having a strong presence in the Arctic,” Olafur Ragnar Grimsson, an ex-Icelandic president who chairs the Arctic Circle forum, the ‘Davos of the Arctic,’ told Reuters.
Reuters could not establish whether the United States was contributing more or less to collective Arctic defence under Arctic Sentry, which is led by Joint Force Command Norfolk, Virginia, established in 2019 with an eye on Russia’s advances in the north.
In response to questions from the news agency, a NATO official said the United States remains a key contributor to NATO’s Arctic defence, noting the commitment was reaffirmed in a joint statement between the Arctic allies in June.
The Pentagon and White House did not respond to Reuters questions for this story, including whether US forces involved in the Arctic defence will be impacted by a US review of troops in Europe.
Along with lingering worries about Trump’s ambitions in Greenland, the security review is expected to cast a shadow over a NATO summit in Ankara in July.
The White House has previously said Trump has prompted allies “to recognse the need to meaningfully contribute to their own defence,” calling the Arctic critical for US national security and the economy.
Russia’s Ministry of Defence did not respond to a request for comment for this story. The Kremlin has in the past said the United States is stoking tensions in the Arctic.
A key challenge for European NATO allies is monitoring activity on Arctic Russia’s Kola Peninsula, neighbouring Finland and Norway.
The peninsula accounts for around two-thirds of Russia’s second-strike nuclear capabilities, including the Russian navy’s Northern Fleet, which operates six of Russia’s 12 nuclear-armed submarines.
From the peninsula, Russia could launch hypersonic missiles towards the United States, making early warning systems vital, or send the submarines towards the US East Coast via the Bear Gap in the Barents Sea and the GIUK Gap between Greenland, Iceland and Britain.
Norway and NATO allies currently monitor the fleet in the GIUK Gap and the Barents Sea, where critical undersea cables have suffered damage in incidents some attribute to Russia.
The Norwegians spy on Kola Peninsula installations and share the intelligence with the Americans.
But NATO must further improve its intelligence, surveillance and reconnaissance capacities, said Mauro Gilli, a professor of military strategy at the Berlin-based Hertie School.
Such abilities do not come cheap in Arctic conditions where standard equipment often fails.
Northern Norway can, for instance, see temperatures drop to -45 deg C in winter ex-wind chill factor.
The Arctic is mostly ocean across Greenland, Iceland, northern Norway and the Barents Sea, so any security presence must be primarily naval, which is costly, said Grimsson.
The United States has only two operational icebreakers. Russia, with by far the biggest Arctic territory, has 42, some nuclear-powered.
Satellite communications that work at high latitudes are crucial to allow real-time detection, Gilli told Reuters, along with long-endurance drones that work in extreme cold, expanded underwater surveillance, and different types of ground-based radars.
He estimated investments could run into hundreds of billions of dollars.
Climate change is making submarine tracking harder, calling for investment in new generations of submarine sensors that can counter changing salinity levels and currents from warming oceans, such as the North Atlantic, which is warming rapidly, according to NATO Defence College research from 2025.
The changes affect how sound travels through water, shrinking the range at which submarines can be detected, the research found.
At the moment “we can listen to and track submarines in the Barents Sea and follow them. If we are not doing that and we lose control of the submarines, then we have a problem,” Norwegian Defence Minister Tore Sandvik told reporters in January.
A Russian intelligence ship was observed monitoring NATO exercises in the North Atlantic and tracked between Iceland and Greenland in June, the Icelandic government said in a statement, underlining Moscow’s own surveillance of the region’s strategic waterways.
There are signs NATO is trying to face up to the challenge.
Nordic countries are among the biggest defence spenders in the alliance and on track to meet NATO’s target of 5 per cent of GDP by 2035.
The US and Finland are teaming up to build up to six icebreakers, the first due in 2027.
Norway is buying frigates and submarines.
The Nordics pooled air forces to create a fleet as large as Britain’s.
Shaken by Trump’s threats to make it a US state and keen to wean itself off a decades-long dependence on US defence support, Canada unveiled a major C$35 billion (S$31.94 billion) Arctic defence plan in March for infrastructure including military airfields in the region.
It is coordinating more closely with Nordic countries and, with Denmark, investing in ice-capable vessels.
Prime Minister Mark Carney told Reuters during a March visit to Oslo that NATO’s focus on Arctic security was overdue but welcome.
British officer Vice-Admiral James Morley, deputy commander of JFC Norfolk, said Arctic Sentry will help more NATO soldiers learn how to operate in harsh polar conditions.
“It provides a much more realistic environment,” Morley told Reuters at the Bardufoss air base in northern Norway, where British Royal Marines train on snowmobiles, skis and helicopters.
Britain is doubling to 2,000 the number of Royal Marines permanently deployed to Norway.
In June, NATO activated a new grouping of 600 soldiers based in Sweden and Finland’s Lapland regions.
However, Iris Ferguson, a former US deputy assistant secretary of defence for Arctic and global resilience between 2022 and 2025, said prioritising the region is difficult.
“When you have a hot war burning in the East, it’s hard to direct investment into a region that doesn’t feel as hot,” Ferguson told Reuters, referring to Russia’s war on Ukraine.
US military leaders taking part in the Arctic Sentry exercise, called Cold Response, tried to reassure European counterparts.
“Our commitment is to defend every last inch of NATO territory,” Major General Daniel Shipley, commander of the US Marine Corps Forces for Europe and Africa, said in Bardufoss, Arctic Norway.
But European leaders’ anxiety is high after Trump’s Greenland threats and talk of withdrawing from NATO.
In May, the US announced cuts to its NATO crisis force contributions including fighter jets, drones and ships.
Norway, traditionally tightly aligned with Washington, joined France’s nuclear deterrence initiative in June.
Norwegian officials now emphasise it is in Washington’s interest to stay engaged, an argument they did not have to make before.
“A hundred kilometres from my border is the world’s largest nuclear arsenal. And it is not directed against me, Mr President, but against you,” Prime Minister Jonas Gahr Stoere said in a speech in February, recalling a conversation with Trump at the White House. REUTERS