It has become evident that disturbances in shipping may have immediate and/or long-term effects
leading to serious economic and political consequences. Under suitable conditions, the necessity of such
disturbances can be quite easily motivated by proclaimed legitimate security concerns. That makes
Sea Lines a potential instrument in Hybrid Conflicts.

Since March 2018, Hybrid CoE/COI VR has taken a closer look at the Hybrid Threats vs. Sea Lines
of Communication in a workstrand consisting of six events. During the process, it was found useful to
propose a taxonomy of maritime hybrid threats that could be used to support various approaches, such as
policy discussions aiming at national or EU/NATO-level responses, planning of operational level exercises
as well as setting requirements for technologies.

This handbook establishes a taxonomy of ten potential
scenarios that were gradually developed and proof-tested during the workstrands.
The Hybrid CoE Participating States advocate a strict adherence to international rules and norms.
They must necessarily observe the legal framework in political or operational responses to what might
be regarded as hybrid threats emerging at sea. Failing that, the consequences might be unintentional and
harsh. Sometimes the events may require a rapid reaction, and decision-makers or maritime operators
need to base their actions on limited information. In this handbook, ten scenarios are presented, each
followed by a short legal analysis. This allows the reader to immediately get on the right track as regards
relevant parts of Law of the Sea and International Humanitarian Law.