Journal on Baltic Security

This article explains the importance of the underwater critical infrastructure as a domain of hybrid warfare operations and the setting for increasing strategic competition. In addition, the article highlights the growing need for NATO and European Union (EU) defense cooperation in this area, particularly to respond to the strategic ambitions of the Russian Federation and its strategic partnership with China as revisionist powers. Taking a pragmatic case study approach, the article evaluates Russia’s current maritime doctrine and characteristic cases of undersea hybrid tactics with several operational examples of Russia’s undersea sabotage capabilities. This leads to outlining the emerging NATO–EU inter-organizational defense cooperation in protecting undersea infrastructure. The article concludes with policy advice that the Baltic states, as small open-to-sea member states, should take an active interest in the capability development of the undersea infrastructure protection in both NATO and EU formats.