In the midst of the snow-covered mountains of Porsangermoen, Norway, 200 U.S. Marines from the Black Sea Rotational Force gathered near a frozen lake last month and, one-by-one, jumped in. Freezing to the point where some later said they could not speak, the Marines used their ski poles to lift themselves out of the frigid water, rolled around in the surrounding snow, and then partook in one final ritual before changing into dry clothes.

They threw back a generous shot of rum.

“It was really cold,” Cpl. Mark Glass told the BBC. “It’s hard to talk and breathe when you’re inside the water.”

Glass and his brethren were enduring the torturous exercise as part of innovative cold-weather training hosted, for the first time, by Britain’s Royal Marines Mountain Leaders, the UK Corps experts in cold-weather.

"This does feel, in the Arctic, a little Cold War-esque." — Heather Conley

U.S. Marines learned how to patrol on skis and snowshoes while still being able to use their weapons. They set up 10-man tents and dug a sleeping chamber into snow banks. They had lessons in analyzing ice thickness, surviving an avalanche and catching and killing food – including reindeer.

The stated purpose of the intensive course was to ready the troops to participate in NATO’s 15,000-man March war games, Exercise Cold Response.

But the training, which took place fewer than 200 miles from Norway’s border with Russia, may have served a dual purpose: preparing the Marines for whatever results from continued Russian aggression in the Arctic.

“This does feel, in the Arctic, a little Cold War-esque,” said Heather Conley, a Senior Vice President at the Center for Strategic and International Studies.

Following incursions into Georgia and the Ukraine during the past decade, and taking a more prominent role in Middle Eastern politics, Russia has slowly turned its gaze toward the Arctic region. Russian bombers have come close to breaching Norwegian airspace on numerous occasions, the Kremlin has decided to reopen and refurbish about 50 Cold War military bases in the area and Russia’s strategic command structure has been reconfigured to include the Arctic.

Russia has said it perceives threats in the region; as polar ice melts, however, Russia’s true ambition may be in establishing a grip on the crucial Northern Sea Route shipping pathway.

“Russia is rushing to nationalize and control new waterways across the Arctic Ocean that could open not simply to commercial shipping, but also military and intelligence activities,” Sen. John McCain, R-Ariz., wrote in a September opinion piece for The Washington Post. “Vast natural resources, including oil and gas, could become available for exploitation, potentially transforming the Arctic into a new theater of geopolitical competition.”

Russia’s massive Arctic coastline is already vitally important to the Russian economy, accounting for 14 percent of Russian GDP and 22 percent of exports, according to Conley. All the more reason Vladimir Putin may aim to shore up and expand his hold on the region.

“Russia’s military activities, as far as I can see, are always aimed at causing concern, and it is very important that we monitor events closely,” Krister Bringeus, Sweden’s ambassador to the Arctic Council, told Defense News. “This is what we are doing.”

As Europe and North America warily watch Russia’s Arctic advance, it’s probably little coincidence the U.S. Marine Corps chose this moment to up its cold-weather proficiency.

“Cold-weather warfighting capabilities are very specialized,” Conley told FoxNews.com. “It’s very small and we need to practice and grow it, because, even if you do a search-and-rescue operation, you’re going to need that expertise in the harshest climates. We’ve, in some ways, allowed that skill to atrophy.”

The Russian response to NATO’s Cold Response war games will also be worth watching. In 2015, the NATO war games only consisted of 4,000 troops and the Russians, given advance notice, were invited to observe the exercises in Norway. But the Kremlin responded by ordering a 45,000-man snap military exercise, with no warning, at full combat readiness.

“This is not a tit-for-tat at all,” Conley said. “I see that Russia is presenting a very different face to us on security in the Arctic, which is creating concerns, which is requiring NATO and individual countries to reassess its own military means.

“Our NATO allies still respect the rules of how we do this; Unfortunately, Russia has chosen not to follow those rules.”