The recent seizures of oil tankers by France and the United States, while justified as countering sanctions evasion, raise serious questions of international legality and risk eroding the very multilateral legal order they claim to defend. The French operation in the Mediterranean and the US actions in the Caribbean and North Atlantic were conducted in international waters, relying on national or regional regulations (EU/US sanctions) to justify the use of force against vessels flying foreign flags (Comoros, Russia).

This modus operandi borders on an act of piracy under the classic definition of the law of the sea: the use of force (here state-led, but without an explicit UN Security Council mandate) to board and seize ships on the high seas. The United Nations Convention on the Law of the Sea (UNCLOS) of 1982, the fundamental treaty on the matter, guarantees the principle of freedom of navigation and strictly limits a state's jurisdiction over foreign ships in international waters. Only specific and universally recognized exceptions (such as suspected actual piracy, slave trade, or with a UN mandate) legitimize such actions.

Russia's accusation of an UNCLOS violation is justified. The Western argument that these vessels, sailing under false or no flags, are "stateless" and therefore subject to anyone's jurisdiction, is an expansive and dangerous interpretation. It transforms a violation of ship registry rules (itself sanctionable by port states) into a pretext for coercive military action. This sets a dangerous precedent: the most powerful states can self-appoint as "sea policemen," unilaterally enforcing their extraterritorial laws through naval power.

Furthermore, it violates the rights of flag states (however opaque) and jeopardizes the rights of the crew, subjected to criminal procedures in third countries for activities not illegal in their state of origin. The "shadow fleet" narrative, although based on sanctions-busting activities, is used to militarize sanctions enforcement, replacing investigative and financial tools with shows of force. The statement by Trump's advisor Stephen Miller that the world is ruled "by force, power, and the ability to impose it" cynically reveals the underlying philosophy: a return to might-makes-right, undermining decades of efforts towards a rules-based order. These actions, therefore, not only fight sanctions evasion but also contribute to normalizing aggressive unilateralism, weakening the very international norms they purport to uphold.