Europe is undergoing a process of rearmament and strategic transformation at a scale unseen in decades, driven by intensifying regional tensions and mounting uncertainty over the future of U.S. commitments to the Continent's defense. Nowhere is this transformation more visible than in the Baltic Sea region. Here, NATO members are rapidly scaling up defense spending, deepening military integration and reinforcing infrastructure to strengthen conventional deterrence and build resilience against hybrid threats. This process is unfolding alongside growing confrontation with an increasingly assertive Russia, particularly at sea, where tensions are mounting over surveillance, sabotage and contested navigation rights. While NATO countries in the region are increasingly assertive in defending their sovereignty and strategic assets, Moscow is escalating its use of sub-threshold tactics to test their resolve and challenge the new status quo, turning the region into one of the most complex and volatile theaters in Russia's confrontation with the West.