WASHINGTON—US authorities have intensified efforts to disrupt the illicit oil trade, seizing at least seven vessels since late last year with links to Venezuela and the broader “shadow fleet” network. This campaign, blending economic pressure with assertive maritime enforcement, targets a complex web of aging tankers transporting oil from sanctioned countries like Iran, Russia, and Venezuela. The increasingly aggressive tactics raise critical questions about the legal basis for these seizures and the logistical challenges of managing the captured vessels.
Financial intelligence firm S&P Global estimates that approximately one in five oil tankers globally are involved in smuggling oil from sanctioned nations. Prior to the recent actions targeting Venezuelan oil, the US Department of the Treasury’s Office of Foreign Assets Control (OFAC) had already sanctioned numerous vessels within this “shadow fleet” for their role in trading Iranian or Russian oil. However, the current enforcement approach marks a significant escalation, with US authorities actively pursuing tankers across international waters, even in proximity to Russian submarines, though not always carrying Venezuelan oil.
On , Sean Parnell, the Pentagon’s chief spokesman, articulated the administration’s strategy on X, stating that US forces would “hunt down and interdict ALL dark fleet vessels transporting Venezuelan oil at the time and place of our choosing.” This approach necessitates addressing two key issues: the legal justification for the seizures and the practicalities of handling seized tankers.
What is the legal basis?
While US authorities have reportedly filed warrants for dozens of tankers linked to the Venezuelan oil trade, only two warrants have been unsealed to date: those authorizing the seizure of the M/T Skipper (formerly the Adisa) and the Bella I (now known as the Marinera). Both vessels were sanctioned for supporting Hezbollah and the Quds Force, a branch of Iran’s Islamic Revolutionary Guard Corps. At least three other seized vessels—the M/T Sophia, the Olina (formerly the Minerva M), and the Sagitta—were sanctioned in due to their connections with Russia.
Sanctions alone do not automatically authorize seizure or confiscation. While the International Emergency Economic Powers Act (IEEPA) grants the US president broad powers to regulate transactions, it does not permit confiscation unless the United States is engaged in an armed conflict. During wartime, IEEPA allows for the confiscation of foreign property used in attacks against the US, and the maritime practice of “prize law” permits the capture of enemy vessels. However, the US does not appear to be relying on wartime authorities in the unsealed warrants. Instead, authorities are utilizing civil forfeiture laws, which allow the government to pursue property suspected of involvement in unlawful activities, such as supporting terrorism or violating sanctions.
The unsealed warrant applications for the M/T Skipper and Bella I cases cite broad US laws prohibiting support for terrorism as the basis for the seizures. These laws have expansive extraterritorial application, unlike US sanctions, which typically require some connection to US jurisdiction. Establishing US sanctions violations may prove challenging given the shadow fleet’s efforts to avoid US involvement, navigating globally without utilizing US persons, dollars, or insurance.
Forfeiture proceedings carry legal risks, as the government must demonstrate, by a preponderance of the evidence, that the property is subject to forfeiture. Claimants—including shipowners, charterers, and cargo consignees—can challenge these proceedings. Victims of terrorism with US court judgments may seek access to blocked property held by the US government. A executive order issued by former President Trump prohibits judicial proceedings against Venezuelan oil revenues held by US authorities, but this protection may not extend to seized vessels. Overturning a forfeiture could expose subsequent buyers to financial losses and sanctions risks.
The seizures also raise questions under international maritime law. While international law generally prohibits countries from boarding and seizing ships from other nations in peacetime, vessels lacking a flag state face challenges in claiming this protection. In the case of the Skipper, Guyana’s maritime authority stated that the ship was falsely flying the Guyanese flag. This has prompted other shadow fleet vessels to quickly adopt the Russian flag, changing ownership and rebranding, even painting the Russian tricolor on hulls mid-voyage. US authorities have thus far remained undeterred by this tactic.
US allies are also increasing maritime seizures. Last month, the French navy intercepted the tanker Grinch in the Mediterranean, detaining its Indian captain. French President Emmanuel Macron indicated the vessel was subject to international sanctions and suspected of flying a false flag. Separately, two crude carriers from the dark fleet were briefly detained in Malaysia before being released. In , France seized another sanctioned tanker, the Boracay, off its west coast, releasing it a few days later.
What happens after the seizure?
Seizing vessels may be the easier part of the equation. While US authorities are reportedly working to sell seized oil, managing oil tankers presents significant logistical hurdles. The experience with seized yachts belonging to Russian oligarchs in —incurring in costs for transporting, storing, and maintaining a single yacht—highlights the potential financial burden.
Selling seized tankers for scrap steel presents logistical difficulties. Secretary of State Marco Rubio’s recent announcement regarding the potential return of seized vessels to Venezuela could address the problem in the short term. However, the US government must develop a sustainable solution to these logistical challenges for any long-term campaign against shadow fleet vessels to succeed.
