NATO’s extended frontline: Towards subregional strongholds and aggregated deterrence

FIIA Briefing Paper, FIIA Publikationer
12/2025
Matti Pesu, blue suit, red tie, glasses, dark brown short hair.
Matti Pesu
Äldre forskare
Iro Särkkä
Äldre forskare

The NATO–Russia frontline has become the strategic fault line in Euro-Atlantic security. The frontline states’ exposure to hostile Russian activities makes them more vulnerable to Russian provocations and outright military aggression than the rest of the alliance.

NATO’s new frontline consists of three subregions: the European Arctic, the Baltic Sea, and the Black Sea. While each region has its own distinct dynamics, they all face the threat of potential Russian aggression and heightened risks of spillover from the war in Ukraine.

Russia’s interests, resources, and objectives vary across the subregions. However, Russian military dominance or aggression in one area would affect the security of other frontline states and alter the strategic dynamics along the entire frontline and beyond.

The relationship between exposed frontline states and better-protected allies in the alliance’s rear area is highly significant for NATO’s internal dynamics. The commitment and contributions of the better-protected allies are essential when it comes to turning the exposed frontline into an advantage for the alliance.

NATO should seize the current momentum by imposing severe strategic dilemmas on Russia in each subregion and by generating frontline-wide “aggregated deterrence” based on strong subregional deterrence and defence postures.

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