Sea drones: warships or weapons? Legal status and implications

Abstract Rapid technological development of autonomous and unmanned systems has impacted all sectors of industry. Now, sea drones capable of delivering force – i.e., designed or equipped to cause injury or damage – are also transforming naval warfare. The tangible effects of their deployment are already witnessed in, for example, the international armed conflict between the Russian Federation and Ukraine in the Black Sea. Despite the ongoing use of sea drones during naval hostilities, however, their legal status, including related rights and obligations, remains unclear under both the law of the sea and international humanitarian law frameworks. This article analyzes the legal classification of sea drones capable of projecting force, examining whether they qualify as warships under Article 29 of the United Nations Convention on the Law of the Sea (UNCLOS) or as means of warfare under Articles 35–36 of Additional Protocol I to the Geneva Conventions. It also discusses the legal implications, showing that the classification of sea drones is not just a theoretical exercise but carries significant legal and operational consequences during both war and peace, such as those relating to sovereign immunity, navigational rights and lawful targeting. The paper argues that, since unmanned sea drones cannot pass the warship test (i.e., the cumulative requirements under UNCLOS Article 29), they should be categorized as naval means of warfare; thus, sea drone regulation can be drawn from the regimes governing naval mines and torpedoes. In conclusion, the paper highlights that the classification of sea drones must also consider their humanitarian implications.