The interpretation of “disputes concerning military activities” under Article 298(1)(b) of the United Nations Convention on the Law of the Sea (UNCLOS) rests on a sensitive balance between the protection of strategic interests of States and the need for peaceful settlement of international disputes. There, an essential issue arises how an adjudicative body acting under Part XV UNCLOS should assess the nature of conducts of State for the purposes of Article 298(1)(b). This issue was vividly raised in the dispute between Ukraine and the Russian Federation with regard to the detention of Ukrainian naval vessels and servicemen. In this regard, both the International Tribunal for the Law of the Sea (ITLOS) and the arbitral tribunal set out in accordance with Annex VII UNCLOS wrestled with this issue. This article examines the manner of the interpretation of the concept of the military activities for the purposes of Article 298(1)(b) by comparing the approaches taken by ITLOS and the Annex VII arbitral tribunal.