Today’s post by Lawfire^® favorite, retired Navy Captain Raul (Pete) Pedrozo, could not be more timely given the announcement today from U.S. Southern Command (SOUTHCOM).  It advised that U.S. military forces launched from USS Gerald R. Ford (CVN 78) had “apprehended Motor/Tanker Veronica without incident.” 

SOUTHCOM went on to explain that: “The Veronica is the latest tanker operating in defiance of President Trump’s established quarantine of sanctioned vessels in the Caribbean, proving the effectiveness of Operation Southern Spear yet again.” It added “The only oil leaving Venezuela will be oil that is coordinated properly and lawfully.”

You may be wondering about the law in situations like this.  Pete, who was one of the experts who authored the 2025 edition of the Newport Manual on the Law of Naval Warfare, is the perfect person to explain what U.S. and international law has to say.  

The law involved is rather complicated so we’re going to divide the discussion into two posts.  Part I will provide some background maternal, and discuss peacetime enforcement measure against sanctioned tankers and cargo.  Part II (which is found here) address wartime measures, and also provides some concluding thoughts.  Here’s Part I:

Maritime Enforcement Measures Against Sanctioned Tankers and Cargo in Peace and War

by Raul (Pete) Pedrozo

I. Initial Enforcement Measures

On November 16, 2025, the U.S. State Department announced that, effective November 24, the Cartel de los Soles would be designated a Foreign Terrorist Organization (FTO). The cartel is headed by Nicolás Maduro and other high-ranking individuals of the illegitimate Maduro regime.

Together with Tren de Aragua, the Sinaloa Cartel, and other designated FTOs, Cartel de los Soles are responsible for terrorist violence throughout the Western hemisphere as well as trafficking drugs into the United States and Europe.

On December 10, 2025, the U.S. Coast Guard seized the M/T Skipper (previously known as M/T Adisa), off the coast of Venezuela after satellite imagery confirmed that the vessel had loaded 1.8 million barrels of heavy crude at Venezuela’s José terminal between December 4 and 5.

The vessel routinely engages in deceptive shipping practices, including false reflagging, Automatic Identification System (AIS) disabling or spoofing, and illicit ship-to-ship transfers. Prior to the seizure, Guyana had notified the International Maritime Organization that the tanker had been delisted. As a result, at the time of the seizure, Skipper was flying a false flag and was therefore a stateless vessel.

The oil tanker was sanctioned by the U.S. Treasury Department in November 2022 under Executive Order 13224 for being part of an international oil smuggling operation that funneled money to the Islamic Revolutionary Guard Corps-Qods Force (IRGC-QF) and Hezbollah.

The United States therefore has jurisdiction over the vessel pursuant to 18 U.S.C. 2339B, 18 U.S.C. 981(a)(1)(G)(i), 18 U.S.C. 981 (b), and 18 U.S.C. 2332b(g)(5). Skipper was seized pursuant to a warrant signed by a magistrate judge of the U.S. District Court for the District of Columbia.

On December 16, 2025, President Trump indicated that the Maduro regime was using revenues from stolen oil to finance acts of terrorism, drug smuggling, human trafficking, murder, and kidnapping throughout the Western hemisphere.

Accordingly, the United States labelled the illegitimate Maduro regime a FTO. The President further announced that all sanctioned oil tankers would be prohibited from entering or leaving Venezuelan ports.

The blocking measure targets forty percent of Venezuela’s 400 tankers that are being used to transport sanctioned crude oil to China and other markets. Oil exports are Venezuela’s primary revenue source that is used to finance the illegitimate Maduro regime and its criminal activities throughout the region.

A second boarding by U.S. forces was conducted on December 20, 2025. The Centuries, a Panamanian-flagged tanker, owned by a Hong Kong-based entity, was carrying two million barrels of sanctioned Petróleos de Venezuela SA (PDVSA) oil when it was seized by the United States in the Caribbean after departing from a Venezuelan port. The vessel itself was not sanctioned and was enroute to Asia to deliver its cargo.

There were conflicting reports on the legal basis for boarding. Some reports indicate that the vessel was falsely flagged and was part of Venezuela’s shadow fleet (and therefore stateless). Other reports indicate that the vessel was stopped and boarded based on consent and that the tanker voluntarily stopped and allowed U.S. forces to board it. Either basis would allow for legal boarding of the vessel.

A third tanker—the Bella 1, a sanctioned shadow fleet vessel operating under a U.S. judicial seizure order—was pursued by U.S. forces after it refused to be boarded in the Caribbean in mid-December. The tanker’s registration was initially unknown, but it subsequently claimed it was registered in Guyana.

Two weeks into the pursuit the vessel changed its name to Marinera and claimed Russian registry. The stateless vessel has a well-documented sanctions record, previously carrying sanctioned oil in support of the IRGC-QF and Hezballah, and was previously flagged in Panama. 

The U.S. Coast Guard was waiting for the availability of a specialized team—Maritime Security Response Team—that is trained to conduct (inter alia) opposed or non-consensual boardings. The stateless vessel was finally boarded and seized off the coast of the United Kingdom on January 7, 2026, despite warnings from the Kremlin that Russian naval assets had been deployed to protect the tanker.

Two additional stateless vessels—the Olina and M Sophia—were seized by U.S. forces on January 9, 2026, after taking departing a Venezuelan port with a cargo of oil. International shipping registries confirmed that the Olina was stateless and is under U.S. sanction for transporting Russian oil.

At the time of the seizure, it was carrying sanctioned Venezuelan oil. The M Sophia is also under U.S. sanctions for transporting illicit Russian oil. The tanker is stateless after Panama cancelled the ship’s registry in 2025.

he M Sophia has operated in the dark (no AIS transmissions) since July 2025, a strong indicator that it is involved in illicit activities. The tanker was loaded with about 1.8 million barrels of Venezuelan crude oil at the time of its arrest.

II. Peacetime Measures

In times of peace, boardings of foreign-flagged vessels are permissible under certain circumstances. The United Nations, regional organizations (like the Organization of American States), and ad hoc coalitions can take appropriate maritime enforcement measures against States and foreign-flagged shipping to maintain or restore international or regional peace and security if there is a threat to the peace, breach of the peace, or act of aggression.

Individual States can also take appropriate maritime enforcement measures against States and foreign-flagged vessels that are engaged in illicit activities or to enforce economic sanctions.

A. United Nations

If the Security Council determines the existence of any threat to the peace, breach of the peace, or act of aggression, it shall make recommendations or decide what measures shall be taken to maintain or restore international peace and security (UN Charter, art. 39).

These measures can be non-military in nature—e.g. economic and political sanctions (UN Charter, art. 41)—or military in nature—e.g., blockade and other operations by military forces (UN Charter, art. 42).

UN maritime enforcement actions have only been authorized by the Security Council on five occasions: Southern Rhodesia in 1965-1966 (UNSCR 217, 221, 232); Iraq in 1990 (UNSCR 661, 665); Federal Republic of Yugoslavia in 1991–1993 (UNSCR 713, 787, 820); Haiti in 1993-1994 (UNSCR 841, 873, 875, 917); and Libya in 2011 (UNSCR 1970, 1973).

Given that China is the largest importer of Venezuelan crude oil, as well as the current political differences between the United States and Russia and China regarding Venezuela—both have accused the United States of violating international law—it is extremely unlikely that the Security Council could agree on imposing a maritime blockade of Venezuelan ports.

B. Boarding Ships at Sea

1. 1. Flag State Consent

Generally, ships operating beyond the territorial sea (with limited exceptions) are under the exclusive jurisdiction of the flag State (UNCLOS, art. 92). The flag State may, however, authorize officials of another State to board vessels flying its flag either sua sponte or on request of another State (NWP 1-14M, ¶ 4.4.4.1.2).

The boarding party must comply with any limitations imposed by the flag State. Additionally, consent to board a vessel does not automatically extend to consent to inspect or search the vessel or to seize persons or cargo (NWP 1-14M, ¶ 4.4.4.1.2).

As the flag State’s representative on board the vessel, the master of the ship may also invite foreign law enforcement authorities to conduct a  boarding (NWP 1-14M, ¶ 4.4.4.1.3). The master’s plenary authority over all activities related to the operation of their vessel at sea includes the authority to allow anyone to come aboard the vessel as a guest (NWP 1-14M, ¶ 4.4.4.1.3).

Master consent does not, however, allow for the assertion of law enforcement authority over the vessel, such as arrest or seizure, and may be withdrawn by the master at any time (NWP 1-14M, ¶ 4.4.4.1.3). If reasonable grounds exist after boarding that the vessel is engaged in illicit activities, the boarding State can request that the flag State provide additional authority to search, arrest, or seize the vessel.

Several news reports indicate that the boarding of the Centuries was based on consent. Note, not all States allow their masters to assent to consensual boardings.

1. 2. Stateless Vessels

During a voyage or while in a port of call, a ship may not change its flag unless there is a real transfer of ownership or change of registry (UNCLOS, art. 92). 2. A ship that sails under the flags of two or more States, using them according to convenience, may not claim any of the nationalities in question with respect to any other State, and may be assimilated to a ship without nationality (UNCLOS, art. 92).

If a warship or other authorized government vessel has reasonable grounds for suspecting that a ship is without nationality, it may stop and board the vessel to verify its status (UNCLOS, art. 110).

Because the vessel is stateless, they are not entitled to the protection of any State and all States may exercise jurisdiction, including all appropriate law enforcement actions, over the vessel beyond the territorial sea (NWP 1-14M, ¶ 3.11.2.3).

U.S. law (46 U.S.C., § 70502) specifically provides for jurisdiction over vessels without nationality or a vessel assimilated to be a vessel without nationality. Conduct that could lead a vessel to be treated as one without nationality includes:

• • the master or individual in charge of the vessel makes a claim of registry that is denied by the nation whose registry is claimed;
  • the master or individual in charge of the vessel fails, on request of an authorized U.S. officer, to make a claim of nationality or registry for that vessel;
  • the master or individual in charge of the vessel makes a claim of registry but the claimed flag State does not affirmatively and unequivocally assert that the vessel is of its nationality; and
  • a vessel aboard which no individual, on request of an authorized U.S. officer, claims to be the master or is identified as the individual in charge, and that has no other claim of nationality or registry (46 U.S.C., § 70502).

Additionally, a vessel that displays no name, flag, or other identifying characteristics may lead the vessel to be treated as one without nationality (NWP 1-14M, ¶ 3.11.2.3).

A vessel may be assimilated to a vessel without nationality if the: (1) vessel makes multiple claims of nationality (e.g., sailing under two or more flags); (2) master’s claim of nationality differs from the vessel’s papers; (3) vessel changes flags during a voyage without flag State approval; or (4) the vessel carries removable signboards showing different vessel names and/or homeports (NWP 1-14M, ¶ 3.11.2.4).

All of the vessels mentioned above are stateless vessels and are therefore subject to U.S. domestic laws that allow for the seizure of the vessel and its cargo (18 U.S.C. 2339B, 18 U.S.C. 981(a)(1)(G)(i), 18 U.S.C. 981 (b), and 18 U.S.C. 2332b(g)(5)).

The Administration has indicated that, after appropriate judicial procedures are complete, it intends to keep the sanctioned oil and tankers it seized off the coast of Venezuela. The crude oil will either be sold, kept, or added to the Strategic Petroleum Reserve, while the tankers will remain under U.S. control.

C. Maritime Quarantine

The United States could also impose a maritime quarantine like the measure successfully applied in 1962 to interdict the flow of Soviet strategic-offensive weapons into Cuba. The quarantine only applied to ships carrying offensive weapons to Cuba and utilized the minimum force required to achieve its purpose.

The quarantine served U.S. interests by defending its interests and security while preserving freedom of navigation to the greatest degree possible. President John F. Kennedy decided to impose a maritime “quarantine” on Cuba to avoid possible negative connotations from declaring a “blockade,” which could be viewed as an act of war by the United States (NWP 1-14M., ¶ 4.4.8).

President Kennedy issued the Proclamation of Interdiction on October 23, 1962, to take effect the following morning:

NOW, THEREFORE, I, JOHN F, KENNEDY . . . proclaim that the forces under my command are ordered . . . [beginning] October 24, 1962, to interdict . . . the delivery of offensive weapons and associated materiel to Cuba. . . . [T]he following are declared to be prohibited materiel: . . . Surface-to-surface missiles; bomber aircraft; bombs, air-to-surface rockets and guided missiles; warheads for any of the above weapons. . . . Any vessel or craft which may be proceeding toward Cuba may be intercepted and may be directed to identify itself, its cargo, equipment and stores and its ports of call, to stop, to lie to, to submit to visit and search, or to proceed as directed. Any vessel or craft which fails or refuses to respond to or comply with directions shall be subject to being taken into custody. Any vessel or craft which it is believed is en route to Cuba and may be carrying prohibited materiel or may itself constitute such materiel shall, wherever possible, be directed to proceed to another destination of its own choice and shall be taken into custody if it fails or refuses to obey such directions. All vessels or craft taken into custody shall be sent into a port of the United States for appropriate disposition. . . . [F]orce shall not be used except in case of failure or refusal to comply with directions, . . . after reasonable efforts have been made to communicate them to the vessel or craft, or in case of self-defense. In any case, force shall be used only to the extent necessary.

A similar proclamation could be issued by President Trump to prohibit sanctioned Venezuelan shadow fleet tankers and PDVSA oil from entering or departing Venezuelan ports. To distinguish the operation from a wartime naval blockade, the maritime quarantine would only be applied to sanctioned shadow fleet tankers and other non-sanctioned vessels carrying sanctioned PDVSA oil.

Ships carrying other commodities would not be affected. Additionally, rules of engagement (ROE) should specify that only minimum force and internationally accepted rules for boarding would be used to enforce the quarantine. U.S. warships enforcing the quarantine should be instructed to use all available communications to hail ships approaching the quarantine line.

These measures include international code signals, flag hoists, blinking lights, radio, and loudspeakers. If a ship does not respond to these communications, the ROE would allow U.S. warships to fire warning shots across the bow of the vessel. If a vessel was still noncompliant after the use of warning shots, disabling fire could be used to damage non-vital parts of the ship.

Once a vessel is stopped, a boarding party will conduct visit and search to inspect the vessel’s manifest and cargo. If the ship resists visit and search, the ROE would allow U.S. forces to seize or destroy the vessel. Any vessel seized would be escorted to an appropriate U.S. port and placed under U.S. Coast Guard control until judicial proceedings against the vessel and its cargo could be instituted.

Although similar to a maritime blockade, quarantine is a peacetime military action that can be clearly distinguished from a wartime blockade. A quarantine is a measured response applied in peacetime to address a crisis-level confrontation that presents an extreme threat to U.S. security interests.

Blockade is an act of war against an identified belligerent. The goal of a quarantine is de-escalation and return to the status quo ante, while the goal of a blockade is to deny and degrade an enemy’s capability with the ultimate end-state being defeat of the enemy.

Finally, a quarantine allows for selective application—it only applies to certain vessels or cargoes. A blockade requires a belligerent to impartially apply it to all ships and all States—discrimination by the blockading belligerent renders the blockade legally invalid (NWP 1-14M, ¶ 4.4.8).

 Part II of this essay which addresses wartime measures, and provides some concluding thoughts from Pete is found here

About the author:

Captain Raul (Pete) Pedrozo, U.S. Navy (Retired), is the Howard S. Levie Chair on the Law of Armed Conflict and professor of international law at the Stockton Center for International Law, U.S. Naval War College. Prof. Pedrozo was the former senior legal adviser at U.S. Pacific Command and served as special assistant to the Under Secretary of Defense for Policy.

Disclaimers:

The views and opinions expressed in this article are those of the author and do not necessarily reflect those of the U.S. Naval War College, the U.S. Department of Defense, or the U.S. Government.

The views expressed by guest authors do not necessarily reflect my views or those of the Center on Law, Ethics and National Security, or Duke University. (See also here).

Remember what we like to say on Lawfire^®: gather the facts, examine the law, evaluate the arguments – and then decide for yourself!

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