The U.S. seizure of the tanker Skipper (previously sanctioned as Adisa) off Venezuela marks an escalation in pressure on Nicolás Maduro and highlights the global "shadow fleet" that helps sanctioned states trade oil. These vessels hide behind opaque ownership, fake flags, and disabled transponders, and analysts estimate they now make up roughly 20% of the world’s tanker fleet. Recent Ukrainian strikes on shadow tankers carrying Russian oil underscore the geopolitical and environmental risks of this parallel market and suggest more aggressive enforcement may be coming.
How the Global 'Shadow Fleet' Shaped the U.S. Seizure Off Venezuela — And Why It Matters
A Venezuelan navy patrol boat escorts Panamanian flagged crude oil tanker Yoselin near the El Palito refinery in Puerto Cabello, Venezuela on November 11, 2025. | Juan Carlos Hernandez/AFP via Getty Images
The United States’ seizure this week of a sanctioned tanker off Venezuela — and the Trump administration’s announcement that it will target additional oil vessels in the area — represents a clear escalation of pressure on President Nicolás Maduro. Washington says the move is aimed at curbing illicit activity, including alleged facilitation of drug trafficking into the United States. But the episode also highlights a far broader phenomenon: the growth of a global "shadow fleet" that lets sanctioned states keep trading oil despite restrictions.
What Happened: The Skipper (Formerly Adisa)
The vessel seized was sailing as the Skipper under Guyana’s flag. U.S. officials note the tanker was previously sanctioned in 2022, when it sailed as the Adisa under Panama’s flag. Reporting indicates the ship made trips to and from Iran last year with stops in China and Syria, and routinely disabled its position transmissions to evade monitoring. Analysts told Reuters the Skipper loaded Venezuelan oil in early December and transferred part of its cargo to another tanker bound for Cuba shortly before U.S. authorities seized it.
The Shadow Fleet: How It Operates
These vessels often rely on opaque ownership structures — front companies and PO boxes in jurisdictions such as the Seychelles or Dubai — and they frequently change names and flags. Many operate without standard insurance, are older and less well maintained than regular tankers, and manipulate transponders and navigation data to avoid detection. As a result, they form an informal, parallel market for global energy trade.
Why Cuba Matters
Cuba has for years depended on Venezuelan oil. Where Havana once used its own tankers, years of poor maintenance forced the island to rely on the shadow fleet. Deteriorating infrastructure and sanctions have strained Cuba’s energy system, producing more frequent blackouts; disrupting these clandestine supply lines is therefore both an economic and a strategic pressure point.
Russia’s Role and Global Scale
Russia’s large-scale use of the shadow fleet after its 2022 invasion of Ukraine dramatically expanded the market. Experts estimate shadow vessels now account for roughly 20% of the global oil tanker fleet — effectively creating a parallel energy trading system that blunts the impact of sanctions.
Environmental, Legal, and Accountability Risks
Officials and analysts warn that these older, poorly maintained ships pose a serious environmental hazard. A major spill would be harder to contain and remediate when no insurer or accountable owner can be identified. Legally, the latest U.S. seizure was notable because it was carried out by the U.S. Coast Guard under a judicial seizure warrant — a law-enforcement action — rather than by the military without clear legal authorization.
Concurrent Strikes in the Black Sea
In recent weeks, Ukrainian forces struck five tankers linked to the shadow fleet that were carrying Russian oil: three in the Black Sea near Ukraine’s coast, one near Turkey, and another off Africa’s west coast. That represents a tactical shift for Kyiv, which had largely avoided targeting commercial shipping. The strikes are high risk: they could provoke Russian reprisals and escalate maritime conflict, and they may also reflect increasing pressure on Ukraine as it loses ground on land and faces international diplomatic pressure.
Coordination, Consequences, and What Comes Next
There is no clear evidence the Caribbean seizure and the Ukrainian strikes were coordinated; the timing appears coincidental. Still, both actions underscore the expanding shadow economy created around sanctions and suggest authorities may be moving toward more aggressive measures to dismantle these clandestine networks. The consequences will be geopolitical, legal, and environmental, and they could reshape how states enforce sanctions and police maritime trade.
Bottom line: The Skipper seizure illuminates an evolving global problem — a shadow fleet that allows sanctioned regimes to keep exporting oil while increasing environmental and legal risks. Expect intensified enforcement and a fraught period of maritime confrontation as authorities try to rein in this parallel market.
