Nordic forces train for the Arctic threat they dread most: warm weather

Sweden’s Subarctic Warfare Center is preparing NATO soldiers to survive and fight through the Arctic’s “fifth season,” a swampy, insect-infested period after the thaw. 

Warm months create logistical nightmares—flooded bogs, collapsing moss, and constant risk of hypothermia—that can slow or immobilize troops and vehicles. With Russia entrenched in the high north, Sweden insists allied troops must arrive able to operate immediately, focusing “on the enemy, not the weather.” 

The Swedish armed forces are rewriting the playbook for Arctic conflict. At its Subarctic Warfare Center near the Arctic Circle, instructors say the real challenge is not winter, but what they call the “fifth season.” The period after the spring thaw turns northern Sweden into a swampy morass of bogs, biting insects and unpredictable water levels. “We realized that if there is going to be a war, it is not going to be over in one winter,” said Sgt. Maj. Fredrik Flink. “You can almost compare it to the jungle.” 

Why “warm” is harder than winter

Winter in the high north is punishing, but frozen ground at least allows for movement. In summer and fall, permafrost prevents drainage, creating waterlogged ground that swallows soldiers and vehicles alike. A single misstep can sink a soldier waist-deep in freezing bog water, soaking boots that may remain wet—or even freeze—by morning. Last year, a group of Danish troops brought the wrong footwear and suffered severe cold injuries.

For many allies, the lesson is stark. “Training in the Arctic, if it’s cold, is easy,” said U.K. Royal Marine commando Gary Goodfellow. “The wet messes everything up.” 

A different way of fighting

The swampy landscape forces soldiers to think differently about warfare. Flink, who has spent decades in the region, said conditions often feel more like tropical operations than Arctic ones. “You can almost compare it to the jungle,” he noted, recalling mosquitoes so dense he could sweep them from the hood of a vehicle by the handful.

Western militaries are adapting. The U.S. Army this year published its first Arctic doctrine in more than half a century. Swedish trainers argue that NATO troops must be able to operate all year, not just in the cold. “It’s a slow learning curve,” admitted Capt. Barney Walker of Britain’s Ranger Regiment after one exercise left his unit slogging through bogs. 

Instructors say the environment itself can be as dangerous as an enemy ambush. Flooded tracks and collapsing moss funnel units onto predictable routes, while solar activity disrupts GPS and communications. Soldiers are taught to rely on maps and compasses, even as drones scour the terrain for heat signatures.

At dawn, Swedish trainers deliberately fly drones over encampments to show how long a unit’s warmth lingers on the ground. Troops respond by pulling camouflage tarps over their positions, but instructors then switch tactics, sending foot patrols to locate them manually. The message, said one Swedish officer, is clear: “If you can hide from us, you can hide from the Russians.” 

Over the past decade, the Subarctic Warfare Center has increased its training hours sevenfold, reaching nearly 7,000 annually. Courses range from skiing and ice-diving in winter to marching and riding amphibious Bandvagn 206 carriers through wetlands in fall. Weapons familiarization includes Swedish-made systems such as the Carl-Gustaf and AT4, designed for mobility where heavy armor cannot pass.

The intent is to export knowledge. Officers who train in Sweden are expected to return home and teach their units. “You don’t only have to deal with the enemy, but also with your own colleagues who don’t know how to fight here,” said Spain’s Staff Sgt. Santiago Gallego. 

Sweden’s calculus in a Russia-shadowed north

With Russia maintaining major bases at Severomorsk, Alakurtti and Pechenga, Swedish commanders say readiness cannot wait. If war erupts, Sweden expects to reinforce Finland’s long border with Russia while NATO allies backfill inside Sweden.

Lt. Col. Anders Killmey, who leads the centre, put it bluntly: “They are not coming here just to survive. They have to be able to contribute… The goal is that they can focus on the enemy, not the weather.” He added that Russian soldiers already live and train in the region, so NATO forces must match them. “Assuming that Russian soldiers live and train there… we must do the same.” 

The exercises also intersect with daily life in northern Sweden, where Sami communities herd reindeer across vast distances. During one drill, machine-gun fire abruptly stopped when a lone reindeer wandered onto the range. For Flink, it was a reminder that mastering the environment means more than surviving the elements. “You don’t only have to deal with the terrain,” he said, “you also have to respect the people who live here.”