The incident was not the first undersea sabotage in the Baltic, and it won’t be the last. That shallow body of water has become a hotspot for targeting critical undersea infrastructure. Over the course of the past decades, major Western economies have become increasingly dependent on the flow of data and energy along the seafloor. Russia has begun to weaponize that dependency, and China looks set to follow suit. The West is belatedly rebuilding its capacity to patrol and protect its undersea infrastructure but still hasn’t adequately grappled with how to deter the growing risks below the waves.