Armed attacks against merchant vessels: ‘Looking behind the Flag’ to find the victim State

Abstract This article argues that a non-flag State can be considered the victim of an armed attack against one or more merchant vessels and thus entitled to the right of self-defence under Article 51 of the Charter of the United Nations. This argument gains momentum in light of the recent Houthi attacks in the Red Sea against ships with diverse nationalities. Traditionally, attacks on merchant vessels have been considered attacks on the flag State due to the latter’s economic interests in the vessels. However, given the prevalence of open ship registries, today over 70 per cent of world tonnage is registered under foreign flags. Consequently, the jus ad bellum concerning armed attacks against merchant vessels necessitates a reassessment. The first section of this article revisits the traditional understanding that only the flag State can be considered the victim of an armed attack on merchant vessels. Hinting at the popularization of open registries, this article then clarifies how the laws of the sea and naval warfare have dealt with this phenomenon. It is remarked that ‘looking behind the flag’, especially in naval warfare, has become inevitable. This realization is then transposed to the jus ad bellum. In doing so, this article examines key references concerning armed attacks against merchant vessel: the Oil Platforms judgment by the International Court of Justice and the 1974 Definition of Aggression. This article also engages with directly relevant State practice. Ultimately, this article demonstrates that these references support the need for the reassessment advanced here.