Amid heightening tensions between Russia and European nations, the government of Norway has approved plans to more than double the number of U.S. Marines permitted within their borders as a rotational training force. Marines have been conducting cold weather training in Norway since January of last year, and while many have attributed the American presence to Russia’s military annexation of Crimea in 2014, Norwegian officials have made a habit of avoiding any mention of it, in favor of emphasizing international cooperation.

To date, the Marine force permitted in Norway has been capped at 300, but this new agreement will increase that figure to 700, allowing for a flow of 400 more Marines into what U.S. Defense officials have called “world-class winter and mountain warfare training.” They too avoided any mention of Russia, or concerns about their aggression in the region in their statements.

However, despite the official rhetoric, Russia seems certain that the Marine presence is being expanded with an eye to Moscow, and they’re responded with their usual bravado. They went on to suggest that Norway permitting a relatively paltry contingent of 700 total Marines into their nation could lead to “an arms race.”

“This makes Norway less predictable and could cause growing tensions, triggering an arms race and destabilizing the situation in northern Europe,” the Russian Embassy said in a statement on its Facebook page. “We see it as clearly unfriendly, and it will not remain free of consequence.”

The U.S. Marines have long used underground caves in Norway as a “pre-position” point, permitting the rapid deployment of combat assets throughout that region of the world. Russia has long claimed that this is a needlessly aggressive stance to maintain, despite their military annexation of Crimean in 2014, prompting the recent surge in European concern about defenses.

Norway shares a border with Russia that stretches some 122 miles, and rotating Marine deployments will be training within 250 miles or so of that border. Although Norway is a member of NATO, thus far the Marine presence within their nation has been held as a separate topic than ongoing efforts to expand and bolster defenses along Europe’s eastern flank, likely as part of a diplomatic effort to keep tensions low between Norway’s government and Moscow. Although fairly small in numbers, these Marines do represent the first foreign troops permitted to train within the nation’s borders since the end of World War II.

The Norwegian Minister of Defence, Frank Bakke-Jensen, addressed the Marine presence in a statement provided to CNN:

In times of crisis and war Norway will rely on US and other allied military reinforcements. This is at the core of Norwegian security policy and is further emphasized by our NATO-membership.