A unit of 300 U.S. Marines stationed in Norway to practice cold-weather operations and develop ally partnerships heard unexpected news Thursday, when the commandant of the U.S. Marine Corps told them to be prepared for something bigger. Much bigger.

Gen. Robert Neller told Marines that “there’s a war coming,” according to Military.com, and it will be a “big-ass fight.”

"I hope I'm wrong, but there's a war coming," Neller said Thursday. "You're in a fight here, an informational fight, a political fight, by your presence."

Neller’s comments come at a time when tensions are running hot between Russia and neighboring NATO countries. In September, Sweden, which is not an official NATO member, conducted its largest military drill in 20 years, featuring 19,000 Swedish troops alongside 1,500 from the U.S., France and other NATO countries. The dramatic military demonstration came while Russia was conducting its own set of massive war games with Belarus. NATO later accused Russia of intentionally underselling the scale of its military exercises on Europe's doorstep, known as Zapad, or “West.”

Tensions have been on the rise since Russia’s annexation of Crimea in March, 2014. Since then NATO has deployed troops to Baltic states and Poland, citing a “changed security environment.” In November of this year, NATO expanded its command centers for the first time since the end of the Cold War.

“Just remember why you're here," Neller told the Marines. "They're watching. Just like you watch them, they watch you. We've got 300 Marines up here; we could go from 300 to 3,000 overnight. We could raise the bar."

The Trump administration’s newly unveiled national security strategy singled out Russia and China as two world powers challenging “American power, influence, and interests, attempting to erode American security and prosperity.”

“The combination of Russian ambition and growing military capabilities creates an unstable frontier in Eurasia, where the risk of conflict due to Russian miscalculation is growing, ”the strategy document stated.