Reports that U.S. forces boarded and seized a large oil tanker off the Venezuelan coast on 10 December 2025 have already prompted accusations of “piracy”, unlawful coercion, and a renewed U.S. assertion of hemispheric dominance. At first glance, this incident may look like a familiar episode in long-running U.S.–Venezuela tensions. But read alongside the new 2025 U.S. National Security Strategy (NSS), the tanker seizure marks the re-emergence of a distinctly unilateral approach to maritime enforcement that merges counter-narcotics, counter-terrorism, and regime-change narratives into a single justificatory frame. This blending of threat categories, a pattern visible in earlier episodes of extraterritorial interdiction, allows the United States to treat a broad range of economic and political targets as legitimate objects of maritime enforcement, even absent Security Council authorisation, flag-state consent, or clear legal bases under UNCLOS.

This piece situates the tanker seizure within the legal frameworks of the UN Charter, UNCLOS, and international case law, while also explaining how the move reflects both continuities and novelties in contemporary U.S. strategy. It concludes by considering whether international law retains the normative resilience to constrain state action when great powers increasingly treat law as optional.

The significance of seizing an oil tanker? 

According to early reporting, U.S. forces intercepted a tanker allegedly involved in sanctioned oil shipments linked to both Venezuela and Iran. Administration officials described the operation as a law-enforcement action grounded in sanctions violations, while Venezuelan authorities condemned the seizure as a breach of sovereignty and a potential act of piracy.

The legality of the incident depends heavily on where the seizure occurred and under what authority. Reports remain ambiguous, but if the vessel was on the high seas, U.S. action requires justification under narrow exceptions under the UN Convention on the Law of the Sea (UNCLOS). If instead it was in Venezuela’s exclusive economic zone (EEZ), or even closer to its territorial sea, the legal constraints are even tighter.

The incident has immediate geopolitical stakes. But it also serves as an early operational manifestation of the 2025 NSS, which explicitly revives and expands a Monroe Doctrine–style view of the Western Hemisphere, elevates sanctions enforcement as national security policy, and integrates economic coercion, territorial control, and maritime interdiction into a broader strategy of “hemispheric security”.

The international law framework

The UN Charter: prohibition on the use of force and sovereignty

Article 2(4) of the UN Charter prohibits the use of force against the territorial integrity or political independence of any state. Boarding and seizing a vessel can amount to a use of force, depending on the circumstances. Here, the key questions would be whether the vessel was in a location where Venezuela’s sovereign rights applied, and whether the U.S. action was coercive in a manner that affects Venezuela’s rights or political independence. Even military actions on the high seas can breach Article 2(4) if they are directed against a state’s assets in a way that has coercive strategic effect. In contrast, limited law-enforcement type actions against private vessels, conducted without escalation and grounded in valid legal authority, may fall short of “force” in the Charter sense.

The U.S. might also argue self-defense under Article 51, especially if it frames the seizure as a necessary measure against transnational threats (terrorism financing, narco-trafficking, armed groups). But self-defence requires an armed attack, and the ICJ has consistently applied that threshold narrowly, including in cases such as Oil Platforms (2003) and Nicaragua v. United States (1986).Unless the U.S. can show the tanker constituted an imminent threat or was directly implicated in attacks, the Article 51 route appears weak.

UNCLOS: when a state may interdict a foreign vessel

Under UNCLOS, the starting principle is clear, namely that ships on the high seas enjoy freedom of navigation and are subject to exclusive flag-state jurisdiction (Articles 87 and 92). Interdiction is allowed only under specific exceptions, including, piracy (Art. 105), slave trade (Art. 99), unauthorised broadcasting, stateless vessels, or reasonable grounds to suspect a ship is engaged in certain illicit activities where authorised by a UN Security Council resolution.

Critically, sanctions violations alone are not grounds for boarding a foreign-flagged vessel. Unless the tanker was stateless or a Security Council resolution authorised interdiction, the U.S. needed either flag-state consent, a treaty-based enforcement regime, or a clear self-defence justification (rare in maritime interdiction cases).

If the tanker was in the Venezuelan EEZ, U.S. interdiction is even harder to justify. The EEZ is not sovereign territory, but coastal states retain exclusive rights over natural resources and jurisdiction over certain economic activities. Boarding a vessel in the EEZ without Venezuela’s consent opens the door to claims of interference in sovereign rights. If the vessel had been inside Venezuela’s territorial sea (within 12 nautical miles), the seizure would be prima facie unlawful absent clear and immediate self-defence.

How an international court might view the lawfulness of the seizure

International courts and tribunals, particularly the ICJ and ITLOS, tend to articulate strict evidentiary standards and narrow readings of exceptions to Charter and UNCLOS rules.

High evidentiary thresholds

In Oil Platforms, the ICJ required convincing evidence that Iranian platforms had been used to support attacks on shipping before it would assess necessity or proportionality. It found the U.S. evidence wanting. The Court would likely adopt similar scrutiny here, considering factors such as whether the sanctions allegations are supported by evidence, whether the tanker was stateless or otherwise subject to interdiction, and whether boarding was the least intrusive available measure possible in the circumstances. Given the current public reporting, the U.S. case would be far from watertight.

Narrow construction of exceptions

Courts consistently read exceptions to navigation freedoms narrowly. Absent Security Council authorisation or flag-state consent, the U.S. would need to demonstrate one of the few UNCLOS exceptions applied, unlikely based on public facts.

Contextual relevance of the 2025 NSS

While courts do not adjudicate national strategies, they do assess the purpose and character of state conduct. That said, and operation that reflects a strategy that reasserts a hemispheric security perimeter, promotes broad sanctions enforcement as national security, and frames regional waters as a zone of privileged U.S. control,
could complicate U.S. arguments that this was a purely law-enforcement operation. Courts are wary when law-enforcement language masks what is essentially coercive geopolitical practice.

Continuity and Change: how the tanker seizure reflects the 2025 National Security Strategy

The 2025 NSS provides the conceptual scaffolding for understanding why this operation occurred, and why it happened in the Western Hemisphere, not elsewhere.

Continuity: primacy, coercive economic tools, maritime enforcement

Several long-term U.S. strategic themes are plainly visible from this seizure. Firstly, economic coercion backed by force. From the tanker wars of the 1980s to counter-piracy to sanctions enforcement, the U.S. has often paired economic tools with limited military action. Secondly, maritime interdiction. The U.S. has a long history of maritime operations to enforce sanctions or interdict perceived threats, though typically with multinational or UN backing. Thirdly, security framing of commerce. Consistent with Oil Platforms, the U.S. tends to treat economic activity and maritime flows as tightly linked to national security. These continuities make the operation unsurprising from a historical or strategic perspective.

What’s new? Hemispheric exclusivity and civilisational framing

In view of the continuities of US foreign policy, the 2025 NSS contains several distinctive pivots.

A revived  and explicit Monroe Doctrine

The strategy openly proclaims a “Trump Corollary” to the Monroe Doctrine, asserting that the U.S. will deny non-hemispheric rivals ownership of critical assets in the Americas. Seizing a tanker allegedly linked to Iranian and Venezuelan networks fits exactly into that expanded rule-set. Where previous administrations masked hemispheric management behind multilateral language, the 2025 NSS articulates a forthright claim of regional prerogative.

Sanctions enforcement as national security, not financial regulation

The 2025 NSS elevates sanctions from a diplomatic tool to a core national-security function. This reclassification makes military-enforced interdiction more likely. The tanker seizure aligns with an NSS vision in which sanctions are strategic instruments, maritime interdiction is an enforcement mechanism, and the Western Hemisphere is a priority theatre for both.

Migration, transnational crime, and “non-state threats” as justification for force

Although the tanker incident is not directly about migration, the NSS’s broader framing of cross-border flows, people, goods, capital, as threats to national cohesion contributes to a worldview in which territorial and maritime control is paramount. The notion of “transnational cartels” or “terror-linked networks” can serve as pliable justification for interdiction.

Contradictions revealed by the NSS 2025 and the seizure from Venezuela 

Several tensions in the 2025 NSS become visible in the tanker seizure. For example, in November 2025, U.S. Central Command publicly condemned Iran for seizing a Marshall Islands-flagged tanker in the Strait of Hormuz, stating that Iran’s forced boarding in international waters “constitutes a blatant violation of international law,” undermining freedom of navigation and the free flow of commerce. CENTCOM called on Tehran to explain its legal basis to the international community, indicating yet again that the Trump administration is at odds with, and is seeking to erode, non-Monroe U.S. strategic traditions such as Wilsonian Internationalism (the core idea being that the U.S. secures its interests by building international institutions, spreading democratic norms, maintaining an aversion to coercive unilateralism, and embedding itself in rule-based global governance), Hamiltonian Commercial Liberalism (the core idea being that U.S. power rests on open global markets, stable economic systems, predictable international rules, and an aversion to forms of coercion), and Jeffersonian minimalism (the core idea being that U.S. security is best served by avoiding overextension, respecting the sovereignty of other states, maintaining narrow and non-imperial commitments, and privileging diplomacy and internal strength over militarised or interventionist approaches).

Sovereignty: double standards 

The NSS champions the sanctity of national sovereignty and non-intervention, particularly against “globalist” or transnational encroachments, while simultaneously affirming U.S. discretion to act unilaterally in the Western Hemisphere. The tanker seizure reinforces that contradiction as Venezuela’s sovereignty claims are dismissed as obstacles to enforcement and U.S. sovereignty claims (e.g., protecting its economy, borders, or political order) are treated as overriding. This asymmetry mirrors patterns long highlighted in ICJ cases and critiques of U.S. exceptionalism.

Law-enforcement narratives as strategic cover

The U.S. may describe an interdiction as a sanctions-enforcement action. But the broader strategic goals, countering Iranian influence, managing hemispheric order, disciplining hostile regimes, are geopolitical rather than regulatory. This gap between claimed purpose and actual motivation is precisely the kind of contradiction courts examine when assessing necessity and proportionality, and which will be exploited by adversaries of the U.S. 

Undermining the rules-based order while claiming leadership of it

The U.S. insists on preserving a system of rules that protect its interests, yet routinely treats those rules as flexible when enforcement targets weaker states. The tanker incident exemplifies this tension, i.e. a state that values freedom of navigation and UN Charter constraints is willing to set them aside when inconvenient.

The resilience of international law to power politics? 

The question is not simply whether the United States has violated international law. It is whether international law retains the normative force to constrain state action when a major power openly embraces unilateralism and regional exceptionalism.

Litigation is possible but unlikely to resolve the problem

Venezuela could bring a case, potentially before the ICJ or ITLOS, if jurisdiction exists. ICJ precedent suggests the Court would reject U.S. self-defence claims absent strong evidence, view sanctions violations as insufficient for interdiction, narrowly construe exceptions to UNCLOS navigation freedoms. But adjudication takes years. In the meantime, the normative and strategic damage spreads.

Diplomatic and multilateral pushback matters

International law often functions through collective political reinforcement, not just judgments. If states respond forcefully through the UN General Assembly, regional organisations, or maritime coalitions, the U.S. may be pressured to recalibrate.

The long game: international law endures by adaptation

International law has historically outlasted periods of great-power unilateralism, from the tanker wars of the 1980s to post-9/11 counterterrorism excesses. Its resilience lies in retaining baseline prohibitions (e.g., on force and interference), incrementally clarifying maritime enforcement rules, offering a forum (in courts and tribunals) where legal evaluation happens outside political cycles. The tanker incident ultimately tests not only the lawfulness of one interdiction, but the durability of a legal order that the 2025 NSS simultaneously relies upon and undermines.

The 2025 NSS and the Venezuela tanker incident: strategically improvisational and institutionally disruptive, or normatively and strategically corrosive?

The U.S. seizure of an oil tanker off Venezuela’s coast exposes a sharp tension at the heart of the 2025 NSS. It reflects a continuity of old tools, sanctions, maritime interdiction, limited uses of force, while introducing a newly explicit hemispheric doctrine and a broadened view of what constitutes a security threat. The 2025 NSS leans heavily into Jacksonian and revived Monroe Doctrine instincts, namely unilateralism, territorial-security framing, hemispheric exclusivity, coercive instruments, and scepticism toward alliances and institutions.

Yet American strategic culture has never been reducible to Monroe. It has long contained counter-traditions, including Wilsonian, Hamiltonian, liberal-internationalist, institutional-realist, that resist spheres of influence and champion alliances, treaties, multilateral enforcement, restraint, and universal rules. We see that these traditions continue to animate other branches of the U.S. government, the professional military, allies, and international civil society. They may ensure that what we are witnessing is a change in the ‘weather’ (i.e. institutionally disruptive, strategically shallow and transient), so to speak, rather than the ‘climate’ (i.e. a permanent and enduring change in norms governing international relations). 

The danger, however, is that even a temporary U.S. turn toward hemispheric unilateralism occurs at the same moment other counter-normative actors, most notably China in the South China Sea, are attempting to reshape the ‘climate’ of international law and international relations itself. A synchronised weakening of legal norms by multiple great powers creates conditions in which coercive unilateralism, territorial exceptionalism, and competing imperial logics can escalate into major international conflict. Whether international law can meaningfully constrain similar actions in future will depend less on courts alone and more on the collective willingness of states and international civil society, currently out in the cold,  to uphold the rules-based international order upon which global stability and security rests.

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