DELTA JUNCTION, Alaska >> After parachuting into the frigid Alaska interior, Capt. Weston Iannone and his soldiers navigated miles through deep snow, finally setting up a temporary outpost on a ridgeline next to a grove of lanky spruce trees that were also struggling to survive.

Darkness was setting in, the temperature had fallen below zero, and the 120 men and women who had gathered as part of a major combat training exercise in subarctic Alaska had not yet erected tents. The supply line for fuel, essential to keep warm through the long night ahead, was lagging behind.

“Everything is a challenge, from water, fuel, food, moving people, keeping them comfortable,” said Iannone, the 27-year-old company commander, as his soldiers shoveled deeper into the snow in search of a solid foundation to put up their sleeping quarters. “This is inherent training — understanding how far we can push physically and mentally.”

The first-of-its-kind exercise this month, involving some 8,000 troops outside of Fairbanks, was planned long before Russia’s invasion of Ukraine but was driven in part by Russia’s aggressive moves in recent years to militarize the Arctic — a part of the world where the United States and Russia share a lengthy maritime boundary.

Tensions have been growing in the region for years, as nations stake claims to shipping routes and energy reserves that are opening up as a result of climate change. Now, with the geopolitical order shifting after Russia’s invasion of Ukraine, the competition over sovereignty and resources in the Arctic could intensify.

On the west coast of Alaska, the federal government is investing hundreds of millions of dollars to expand the port at Nome, which could transform into a deepwater hub servicing Coast Guard and Navy vessels navigating into the Arctic Circle. The Coast Guard expects to deploy three new icebreakers — although Russia already has more than 50 in operation.

And while the United States has denounced Russia’s aggressive military expansion in the Arctic, the Pentagon has its own plans to increase its presence and capabilities, working to rebuild cold-weather skills neglected during two decades of war in Iraq and Afghanistan. The Air Force has transferred dozens of F-35 fighter jets to Alaska, announcing that the state will host “more advanced fighters than any other location in the world.” The Army last year released its first strategic plan for “Regaining Arctic Dominance.”

The Navy, which this month conducted exercises above and below the sea ice inside the Arctic Circle, also has developed a plan for protecting U.S. interests in the region, warning that weakness there would mean that “peace and prosperity will be increasingly challenged by Russia and China, whose interests and values differ dramatically from ours.”

The preparations are costly in both resources and personnel. While Iannone’s company was able to finish setting up tents before midnight and survived the night without incident, other companies did not fare so well: Eight soldiers suffered cold-weather injuries, and four soldiers were taken to a hospital after a fire inside a personnel carrier.

Meanwhile, at another recent cold-weather exercise, in Norway, four U.S. Marines died when their aircraft crashed.

Russia, whose eastern mainland lies just 55 miles across the Bering Strait from the coast of Alaska, for years has prioritized an expanded Arctic presence by refurbishing airfields, adding bases, training troops and developing a network of military defense systems on the northern frontier.

With a warming climate shrinking sea ice in the region, valuable fish stocks are moving northward, while rare minerals and the Arctic’s substantial reserves of fossil fuels are becoming a growing target for exploration. Boat traffic is poised to increase from both trade and tourism.

Two years ago, Moscow brought its own war games barreling through the Bering Sea, with Russian commanders testing weapons and demanding that American fishing boats operating in U.S. fishing waters get out of the way — an order the U.S. Coast Guard advised them to comply with. Russia has repeatedly sent military aircraft to the edge of U.S. airspace, leading U.S. jets to scramble to intercept them and warn them away.

This month, in response to escalating international sanctions against Russia, a member of the Russian parliament demanded that Alaska, purchased by the United States from Russia in 1867, be returned to Russian control — a possibly rhetorical gesture that nonetheless reflected the deteriorating relationship between the two world powers.

For centuries, the vast waters of the offshore Arctic were largely a no man’s land locked in by ice whose exact territorial boundaries — claimed by the United States, Russia, Canada, Norway, Denmark and Iceland — remained unsettled. But as melting sea ice has opened new shipping pathways and as nations have eyed the vast hydrocarbon and mineral reserves below the Arctic sea floor, the complicated treaties, claims and boundary zones that govern the region have been opened to fresh disputes.

Canada and the United States have never reached agreement on the status of the Northwest Passage between the North Atlantic and the Beaufort Sea. China, too, has been working to establish a foothold, declaring itself a “near-Arctic state” and partnering with Russia to promote “sustainable” development and expanded use of Arctic trade routes.

Russia has made it clear it intends to control the Northern Sea Route off its northern shore, a route that significantly shortens the shipping distance between China and northern Europe. U.S. officials have complained that Russia is illegally demanding that other nations seek permission to pass and threatening to use military force to sink vessels that do not comply.

“We are stuck with a pretty tense situation there,” said Troy Bouffard, director of the Center of Arctic Security and Resilience at the University of Alaska Fairbanks. “Either we acquiesce to Russia, to their extreme control of surface waters, or we elevate or escalate the issue.”

The focus in recent years had been to expand diplomatic channels, collaborating on a range of regional challenges through the Arctic Council. That work was put on pause, however, after Russia invaded Ukraine.

In Nome, which hopes to position itself as a maritime gateway to the Far North, there has long been evidence that a new era for the Arctic was arriving. Mayor John Handeland said winter sea ice that once persisted until mid-June may now be gone by early May and does not reappear before Thanksgiving.

A record 12 cruise ships docked in Nome’s existing port in 2019. That number was poised to double this year, although some cruises that had expected to sail along Russia’s northern coast have canceled plans. For Handeland, the time is right to strengthen U.S. capabilities.

“As things escalate, I think the need for expansion of our military is now,” Handeland said. “I think we kind of had a period of time where we thought everything was cool, that we can let our guard down, so to speak. And now we’re seeing that that maybe was not a wise idea.”

But there are multiple local constituencies to navigate as development moves farther into the Arctic. Alaska Natives are wary about effects to the region’s fragile environment, on which many depend for hunting and fishing, said Julie Kitka, president of the Alaska Federation of Natives.

“I think that our people realize that our military needs to protect our country and our military does need to invest in a presence in the Arctic,” Kitka said. “But it has got to be done smart.”

Dan Sullivan, Alaska’s junior Republican U.S. senator, said that while there may be little threat of a Russian invasion of Alaska, there is concern about Russia’s military buildup in the region.

“Ukraine just demonstrates even more, what matters to these guys is presence and power,” Sullivan said. “And when you start to build ports, when you start to bring up icebreakers, when you start to bring up Navy shipping, when you have over 100 fifth-gen fighters in the Arctic in Alaska, we’re starting to now talk Putin’s language.”

Alaska is already one of the nation’s most militarized states, with more than 20,000 active-duty personnel assigned to places such as Eielson Air Force Base and Fort Wainwright in the Fairbanks area, Joint Base Elmendorf-Richardson in Anchorage, and Coast Guard Air Station Kodiak. The Army’s large training exercise — the first Combat Training Center rotation to be held in Alaska — took place around Fort Greely, about 100 miles southeast of Fairbanks. Alaska is also home to critical parts of the nation’s missile-defense system.

Bouffard said the fracture in relations caused by Russia’s invasion of Ukraine could open the door to a variety of future problems that can only be guessed at right now. While there is no imminent conflict in the Arctic, there could well be friction over how Russia manages offshore waters or disputes over undersea exploration. The United States also needs to be prepared to aid northern European allies that share an uncertain future with Russia in Arctic waterways, he said.

That will mean being prepared for a range of potential problems. In a separate Alaska military exercise in recent weeks, teams from the Marines and Army practiced cold-weather strategies for containing chemical, biological, radiological and nuclear contamination.

At the large Army war games exercise near Fort Greely, the soldiers rehearsed a scenario in which paratroopers seized control of an airfield and established operations to hold the new territory. An opposing force then mobilized to try to reclaim the area.

Portable heating elements were used to keep engines running, along with lubricants that work in subzero temperatures. Some soldiers used skis and snowshoes to get around, as well as snowmobiles and small-unit support vehicles light enough to traverse deep snow.

For many of the soldiers under Iannone’s command, defending the airfield meant establishing positions in remote areas with more rudimentary means. One heavy weapons group chopped down trees by hand and used a sled to pull a bulky Improved Target Acquisition System to a vantage point from which the soldiers could scan miles of landscape below.

They erected a tent with a small stove heater, shielded with a wall of snow on all sides. They rotated in hourly shifts outside the tents — every half-hour at night — in order to keep warm.

Even then, 21-year-old Spc. Owen Prescott said he had struggled with the bite of nighttime cold and was figuring out the appropriate layers to wear to stay warm as temperatures neared minus 20. As he spooned some steaming food from a freeze-dried Army ration, he said he and his colleagues were focusing much of their attention on making sure they did not become a cold-weather casualty before engaging on their hypothetical combat mission.

“It’s just dealing with the cold, sustaining in the cold,” said Prescott, who is from Southern California. “I’m used to wearing shorts and flip-flops my entire life.”

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