Abstract Armed conflicts often spill over from the land to the sea, rendering the law of naval warfare key for governing such conflicts. Against this background, the United States Naval War College developed the Newport Manual on the Law of Naval Warfare (Newport Manual) in 2023, which attempted to codify the existing rules of customary international law. However, this manual differs from the San Remo Manual on International Law Applicable to Armed Conflicts (San Remo Manual), adopted in 1994, particularly regarding the rights of neutral coastal States over their exclusive economic zones (EEZs). While the San Remo Manual requires belligerents to have due regard for such rights, the Newport Manual assumes that such due regard is not required under customary international law. These divergences are derived from different understandings of the relationship between the United Nations Convention on the Law of the Sea (UNCLOS) and the law of naval warfare. This article analyses this by examining the two manuals as well as the domestic military manuals of maritime powers. It concludes that due regard should be paid to neutral States’ EEZ rights, but the standard of due regard during an armed conflict differs from that applicable during peacetime.
Makoto Seta (2025) studied this question.