The increasing sabotage and unfriendly, illegal or even terrorist activities against vessels or port facilities in marine areas have occasioned intensive discourse on ‘hybrid’ naval warfare. Using all possible means—not only weapons—in an armed conflict to damage an enemy’s interests has long been considered an option in any war. However, the current use of the expression ‘hybrid warfare’ denotes methods and means that have become more available due to recent technological developments. As regards hybrid naval warfare, the main legal issue is whether these developments necessitate revision of two main branches of international law, namely the law of the sea and the law of armed conflict. The present hypothesis is that international law is still sufficiently equipped with the rules necessary for addressing the challenges of a hybrid naval war. Any attempt to expand the possibility of use of force in international relations under the pretext of new threats should be discouraged.