Capt. Monica Glenzer/U.S. Army 8th Theater Sustainment Command, National Security Law Team
United States naval forces continue to demonstrate the reach and resolve required to counter illicit maritime activity globally. Nearly 20% of tankers worldwide are used to smuggle oil. The U.S. Department of War announced that it “will deny illicit actors and their proxies freedom of maneuver in the maritime domain.” Resulting U.S. interdictions of stateless shadow fleet tankers are in accordance with international law, specifically the law of the sea.
In February 2026, the U.S. Navy’s 7th Fleet tracked, intercepted and boarded three such oil tankers. The vessels departed Venezuelan waters and attempted to evade a quarantine that the U.S. imposed on illicit oil shipments. The U.S. tracked the tankers, after they left the Caribbean, to the Indian Ocean and conducted right-of-visit boardings.
The tankers are part of a shadow fleet that transported Venezuelan crude oil to overseas markets. The network of tankers and shell companies is designed to obscure the origin, ownership and destination of illicit oil. Shadow fleet vessels frequently disable tracking systems, falsify registration, change names and flags, and conduct ship-to-ship transfers in international waters to evade detection. Among other things, the shadow fleet enables oil exports from states under international sanctions, including Iran, Russia and Venezuela, and routes shipments to buyers despite international restrictions.
China has sought to characterize the U.S. interdiction operations as unlawful interference with maritime commerce and an overreach of U.S. authority on the high seas. Such spurious claims, however, overlook a key legal distinction — that stateless vessels are not entitled to flag-state protection.
The United Nations Convention on the Law of the Sea (UNCLOS) provides clear authority for a “right of visit,” permitting warships to board vessels on the high seas when there are reasonable grounds to suspect that the ship is without nationality. Because vessels must display their state flag on the high seas, stateless vessels fall outside the normal protections of flag-state jurisdiction and may be subject to boarding, inspection and enforcement actions by other states. Further, many shadow fleet vessels operate under false or manipulated registry, effectively rendering them stateless.
The three tankers interdicted in February fit this profile. The ships claimed false flags, sought to obfuscate their identities, and employed deceptive practices linked to entities that evaded sanctions and transported oil illegally. The tankers exposed themselves to right-of-visit boardings. In interdicting the vessels, the U.S. applied established maritime law to deter sanctions evasion.
As shadow fleets expand and adapt, enforcement actions grounded in UNCLOS remain essential for maintaining a free, secure and prosperous Indo-Pacific. The U.S. interdiction operations represent not a deviation from international law, as China erroneously asserts, but instead demonstrate the U.S.’s commitment to its Allies and Partners and to international law.