This Hybrid CoE Paper examines recent developments in maritime hybrid threats through four sets of escalating scenarios and accompanying legal scans. The publication addresses critical undersea infrastructure (CUI) disruptions, drone interference, fishing boat disruption, and shadow fleet operations, analysing how existing international law applies to contemporary challenges in the maritime domain. The legal scans address questions related to jurisdiction, maritime interception operations, self-defence, collective defence, sanctions enforcement, and state responsibility.
The paper highlights the growing importance of common interpretations of international law, coordinated multi-flag operations and shared situational awareness in countering maritime hybrid threat activity and sanctions evasion. The paper concludes that more legal options are available to counter hybrid threat activity in the maritime domain than is commonly assumed.




