Russian forces have been beefing up bases and building military infrastructure near the Finnish border, according to recent satellite imagery, in moves that could reveal their strategy for what happens after the Ukraine war.

The imagery, confirmed by NATO officials, shows row after row of new tents; new warehouses that can store military vehicles; renovations to fighter jet shelters; and steady construction activity on a helicopter base that had been mostly unused and overgrown.

So far the moves seem to be the early stages of a larger, longer-term expansion, and NATO officials say this is nothing like the buildup along the Ukraine border before Russia’s full-scale invasion in 2022. For now, Russia, preoccupied with its war in Ukraine, has very few troops along the frontier, and the Finns insist that none of this is much of a threat — yet.

But Finland is one of NATO’s newest members, joining two years ago, and the moves no doubt reflect Moscow’s own perception of a threat: This 830-mile frontier is now the Western alliance’s longest line of contact with Russia. Military analysts predict it could become a hot spot, especially with much of it lying in the increasingly contested Arctic Circle.

American and Finnish troops recently held an elaborate Arctic war game in this region, with hundreds of troops running around the woods and the Finns zipping through the trees on cross-country skis. The presumed enemy? Russia.