Selective sovereignty at sea: What the US seizure of Russian oil tanker tells about global order

A seizure with systemic implications

- By P.M. Amza

Russian oil tanker

THE recent seizure by the United States of a Russian-flagged oil tanker on the high seas has drawn sharp diplomatic protest from Russia, but the real significance of the episode lies well beyond the immediate bilateral dispute.

At its core, the incident raises a fundamental question confronting the contemporary international system: can a State unilaterally enforce its domestic sanctions regime on the high seas without multilateral authorisation?

On the surface, the episode may appear technical—one vessel, one interception, one diplomatic exchange. Yet history shows that seemingly isolated maritime incidents often signal deeper shifts in how power is exercised and justified. For maritime trading nations and smaller states, the stakes are particularly high, because the law of the sea has long functioned as one of the few domains where rules have meaningfully restrained power.

Flag-state jurisdiction: The bedrock of maritime order

Modern maritime governance rests on a clear and long-established rule: a vessel operating on the high seas is subject almost exclusively to the jurisdiction of the state whose flag it flies. This principle, codified in the United Nations Convention on the Law of the Sea (UNCLOS), emerged from centuries of conflict, competition, and negotiation over control of the oceans.

The purpose of flag-state jurisdiction is not to privilege any particular power, but to ensure predictability. Without it, the seas would revert to a condition where the strongest navy could impose its will on commercial shipping, undermining global trade and security alike. In legal terms, therefore, a Russian-flagged tanker operating beyond territorial waters remains under Russian jurisdiction, irrespective of political disputes over its cargo or destination.