Following the incident, Ukraine instituted arbitration proceedings against Russia under Annex VII to the United Nations Convention on the Law of the Sea (“UNCLOS” or the “Convention”). Ukraine alleged that Russia had breached its obligations under UNCLOS, particularly in respect of the immunity of foreign naval vessels.

On 16 April 2019, Ukraine filed a request for provisional measures with ITLOS. Specifically, Ukraine requested ITLOS to order Russia to: “(a) [r]elease the Ukrainian naval vessels […]; (b) [s]uspend criminal proceedings against the twenty-four detained Ukrainian servicemen and refrain from initiating new proceedings; and (c) [r]elease the twenty-four detained Ukrainian servicemen and allow them to return to Ukraine” (see Provisional Measures Order, paragraph 23).

The Annex VII arbitral tribunal that will eventually hear Ukraine’s claims has yet to be constituted. Nevertheless, Article 290(5) of UNCLOS provides that “[p]ending the constitution of an arbitral tribunal to which a dispute is being submitted under this section, […] the International Tribunal for the Law of the Sea […] may prescribe, modify or revoke provisional measures […] if it considers that prima facie the tribunal which is to be constituted would have jurisdiction and that the urgency of the situation so requires […]”.

ITLOS’ prima facie assessment of the Annex VII tribunal’s jurisdiction revolved around the potential applicability of the “military activities” exemption contained in Article 298(1)(b) of UNCLOS. This Article provides that States may declare that they do not accept compulsory dispute settlement procedures under UNCLOS in respect of “disputes concerning military activities”. Russia, like Ukraine, had made such a declaration. On that basis, Russia argued that, since the incident concerned “military activities”, the dispute was excluded from the Annex VII tribunal’s jurisdiction.

ITLOS rejected Russia’s argument and found that the incident concerned law enforcement rather than military activities. ITLOS reasoned that the distinction between these two activities had to “be based primarily on an objective evaluation” (see Provisional Measures Order, paragraph 66). It followed that neither a party’s own description of the activities nor the type of vessel used was necessarily determinative. And, indeed, ITLOS seemed to disregard Ukraine’s prior characterisation of the incident as an “attack”, an “act of aggression” and an “unlawful use of force” (see Russia’s Memorandum, paragraph 32). Accordingly, ITLOS was satisfied that the Annex VII tribunal has prima facie jurisdiction.

ITLOS then considered two additional conditions for the prescription of provisional measures under UNCLOS Article 290(5): (i) the plausibility of the rights asserted; and (ii) the real and imminent risk of irreparable prejudice.

As to the first condition, the rights concerned the immunity of warships and naval auxiliary vessels under the Convention. Two of the vessels appeared to be warships. The other appeared to be used “only on government non-commercial service”, as referred to in Article 96 of the Convention. ITLOS was therefore satisfied that the rights claimed by Ukraine were plausible.

As to the second condition, ITLOS found that “any action affecting the immunity of warships is capable of causing serious harm to the dignity and sovereignty of a State” (see Provisional Measures Order, paragraph 110). Furthermore, the continued imprisonment of the Ukrainian servicemen raised humanitarian concerns.

As a result, ITLOS found that the urgency of the situation required the prescription of provisional measures, including the immediate release of the three vessels and the 24 servicemen. However, it did not consider it necessary to order Russia to suspend the criminal proceedings.

ITLOS’ approach to this case is based on a narrow interpretation of “military activities”, thereby setting a high threshold for the application of the jurisdictional exclusion foreseen in UNCLOS Article 298(1)(b). Although this is only a prima facie finding, the order will give pause to the 27 States that have made a declaration under that Article, including the United Kingdom and China. It is also important for other countries that, like the United States (see United States Congress, Executive Report 110-9, Section VIII), intend to make such a declaration once they accede to the Convention.