This past October, NATO troops joined forces with nations friendly to the alliance to conduct the largest joint military exercise assembled by the organization since the end of the Cold War: Trident Juncture 18.

The drills, which took place in and around the Baltic and Norwegian Seas, were meant to offer the varied military forces a glimpse of what a full-scale war with a nation like Russia might be like. And as U.S. forces learned in particular, fighting a war in the frigid waters of the North Atlantic is a far cry from nearly two decades worth of combat operations from the comparably calm and toasty Persian Gulf.

“When I was in the States [prior to the exercise], people asked me, ‘Hey, why’d you do this in October and November? It’s pretty nasty and cold in the high north at that time of year,'” U.S. Navy Adm. James Foggo, commander of U.S. naval forces throughout Europe and Africa, told the press. “That’s exactly why. We wanted to stress the force, and we truly did get some lessons learned out of this.”

It would seem Admiral Foggo got what he was after. Nearly immediately, before the drills even began, the U.S. military began showing signs of its discomfort operating in such a different environment than service members have trained for throughout the Global War On Terror. Heavy North Atlantic seas damaged the amphibious landing ship USS Gunston Hall, forcing it to return to port in Iceland before it could even make it to the drills. Soon thereafter, another amphibious landing ship, the USS New York, was also forced to return to port in Iceland to flee the ocean’s heavy chop. Then, as the drills were about to commence, four U.S. Soldiers were injured in Norway when three of their vehicles collided and the fourth skidded off the road and overturned while attempting to avoid the pileup.

“We’ve been operating in the Persian Gulf, where it’s like a lake, and it’s really hot, whereas now we’re operating up off the coast of Norway, where it’s blowing a gale, the decks are moving around, the ships are getting beat up, and the people are getting beat up,” said Vice Adm. Andrew Lewis, commander of the Navy’s recently returned-from-the-dead 2nd Fleet. The 2nd Fleet was reactivated over recent months due to a sharp upturn in Russian submarine activity throughout the Atlantic.

“We’re not used to being out on the flight deck for long periods of time where it’s really cold,” Lewis continued. He would know, prior to pinning on admiral, Lewis served as a pilot aboard the Navy’s carriers.

Despite damage to two vessels, four vehicles, and the injuries that accompanied these incidents, the U.S. and NATO have both characterized the exercises as a success — and with good reason. The intent behind sending 50,000 troops along with thousands of aircraft and naval vessels to the unforgiving north was to identify shortcomings, provide valuable experience to service members, and continue to develop cooperation between friendly states.

The United States military is a massive enterprise, and like its flag ship super carrier the USS Gerald R. Ford, its size makes it difficult to “turn on a dime.” The U.S. is transitioning away from counter-insurgency and anti-terrorism operations and back toward near-peer level conflicts. That transition can’t happen over night.

Russia has placed a heavy military emphasis on the Arctic, taking advantage of melting sea ice to establish new shipping lanes and littering the region with military installations to assume sovereignty over said lanes. In the decades to come, the Arctic promises to be among the most hotly contested regions of the globe, and the U.S. finally seems to be aware of it. However, awareness isn’t enough to deter a future conflict — preparation is required. Trident Juncture saw the first U.S. aircraft carrier sail above the Arctic Circle since the early 90’s — if the U.S. hopes to be able to stand and swing in the North Atlantic, training in the region needs to become far more commonplace.

“Our kids, they adapt really quickly, but not without repeat efforts,” Lewis said. “I think most of it’s been … those kind of lessons, and I think overall we did pretty well, but we can do better.”