In a decade in which the term “blockade” is being liberally but ambiguously employed — Russia-Ukraine, Gaza, Venezuela, and Iran — the so-called blockade of Cuba stands out in terms of longevity, effectiveness, and (at least as a matter of international law) legal ambiguity. Applied to Cuba, the term is rhetorically significant but legally imprecise. This is not least because, whereas all the other uses of the term have tended to be associated with armed conflict, the Cuban measures are not — or so far not. They have instead operated principally through tariffs, sanctions, diplomatic pressure, and the deterrent effect of related maritime-enforcement actions directed at Venezuela, Iran, and Russia-linked oil networks. For reasons to be explained, the term “embargo” better suits the U.S. actions.
Such measures have a long lineage in the Cuban context. They extend from the 1962 Presidential Proclamation 3447 (issued under the Foreign Assistance Act of 1961) and the “Quarantine” of the same year, through the 1996 Helms-Burton Act and the two Trump administration “maximum pressure” campaigns — the first initiated by NSPM-5 in 2017 and the second reaffirming and amending that presidential memorandum in 2025.
In January 2026, Executive Order (EO) 14380 authorized additional duties on goods imported from countries determined to have directly or indirectly purchased or received Cuban oil, or otherwise provided oil to Cuba. The U.S. Supreme Court subsequently struck down certain tariffs, including those in the order. Still, the national emergency that the order declared remains in effect, as do sanctions mechanisms under Helms-Burton and related instruments. Tellingly, the U.N. General Assembly has, for decades, annually adopted a resolution calling for an end to the “Cuba Embargo,” most recently in Resolution 80/4 (2025) (adopted 165-7-12).
To date, there has been no recorded seizure or boarding of a vessel pursuant to the Cuba-oil authorities themselves, as distinct from earlier interdictions under Venezuela and Iran sanctions that incidentally affected shipments bound for Cuba. This is not to say that the oil embargo has been ineffective. On the contrary, its deterrent effect has been strong. For instance, at least one tanker carrying temporarily non-sanctioned Russian oil, originally bound for Cuba, reportedly diverted from its intended course in light of the new U.S. measures. Similarly, one of Cuba’s non-sanctioned oil sources — Mexico — has now ceased oil shipments to Cuba, in a move widely interpreted as a response to U.S. pressure and the new tariff threat. Indeed, it was the arrival in Havana of a Mexican oil tanker that apparently prompted President Trump’s January 11, 2026, “THERE WILL BE NO MORE OIL OR MONEY GOING TO CUBA – ZERO!” Truth Social post.
The December 2025 seizure of tankers involved in the Venezuela oil trade, especially after the January embargo, further exacerbated Cuba’s oil crisis (see here and here). But curiously, in late March, the Russian-flagged Anatoly Kolodkin was allowed to berth in Cuba, with Trump stating, “We don’t mind having somebody get[ting] a boatload, because they have to survive. … If a country wants to send some oil into Cuba right now, I have no problem … because the people need heat and cooling and all of the other things that you need.”
The “effectiveness” of the embargo in terms of at-sea enforcement appears to rest primarily in the parallel sanctions regimes that the United States has imposed on other oil-exporting States servicing Cuba, including Iran, Venezuela, and Russia. For instance, the Skipper, seized in December 2025 (see here, and here), had just a few days earlier carried out an at-sea ship-to-ship transfer of some of its oil to Neptune 6, which was believed to be enroute to Cuba. That seizure was characterized and processed domestically in the United States as an enforcement and forfeiture activity based on the Venezuela sanctions; the Cuban dimension seems to have been incidental. Similarly, the seizures of Marinera / Bella 1 and Sophia also appear to have been based on the Iran and Venezuela oil sanctions schemes, rather than any implementation of the Cuba oil embargo. It is of legal significance, therefore, that there have (it would appear) been no vessel seizures in international waters that are directly tied to the purported Cuba oil embargo.
The Trump administration has been candid about its political objective: regime change in Cuba. Secretary of State Marco Rubio signaled as much within hours of Venezuelan President Nicolás Maduro’s capture in January 2026, saying that he would be “concerned at least a little bit” if he were in their government. Soon thereafter, Trump took to social media to warn Cuba to “make a deal, BEFORE IT IS TOO LATE” and endorsed a post suggesting Rubio should become Cuba’s President: “Sounds good to me!” By March, he was telling CNN that “Cuba is going to fall soon.” And EO 14380 itself provides that the tariff mechanism may be modified if Cuba or an affected country “align[s] sufficiently with the United States on national security and foreign policy matters.”
The consequences for Cuba’s civilian population have been severe. U.N. human rights experts have pointed out that blackouts are already lasting up to twenty hours in many areas. The situation has dramatically worsened, with the national electrical grid suffering several total collapses, leaving approximately 10 million people without power. Cuba suspended refueling at its airports, triggering flight cancellations; schools and universities closed; and hospitals reported an inability to perform thousands of scheduled procedures. U.N. Secretary-General António Guterres warned through his spokesman that the situation “will worsen, and if not collapse, if its oil needs go unmet.” The same group of U.N. human rights experts went further, condemning EO 14380 as “a serious violation of international law” that “risks constituting the collective punishment of civilians.”
In this article, we examine the international law dimensions of the U.S. campaign against Cuba. As we will explain, whatever one calls what the United States is doing — blockade, embargo, oil denial campaign — it is not a “blockade” in the sense of the law of naval warfare, for no international armed conflict with Cuba exists. The applicable bodies of law are instead the U.N. Charter’s prohibition on the threat or use of force and the customary international law rule of non-intervention.
Blockade Under the Law of Naval Warfare?
As we have previously discussed in relation to Venezuela, a blockade — in the law of naval warfare (LoNW) sense — is “an operation by a belligerent State to prevent vessels and/or aircraft of all States, enemy as well as neutral, from entering or exiting specified ports, airfields, or coastal areas belonging to, occupied by, or under the control of an enemy belligerent State” (DOD Law of War Manual, § 13.10; see also Newport Manual on the Law of Naval Warfare, Drew). However, unlike the Venezuela situation, there is no blockade of Cuba because 1) there is no ongoing international armed conflict (IAC) between Cuba and the United States, and 2) the U.S. actions themselves do not qualify as a blockade triggering such a conflict (see, e.g., the 1862 Prize cases; see section “Blockade Triggering International Armed Conflict?”) and its rules on blockade.
The first trigger — the existence of an IAC between the United States and Cuba — is simply absent. It is interesting to note how the recent State Department legal advice on the Iran war asserts the existence of an elongated but staccato IAC between Iran and the United States (on which, see here). Still, even if this were a valid argument in that context (which we do not believe it is), the United States-Cuba situation would not qualify. For it to do so would require some form of continuity in the occasional use of armed force from the 1961 Bay of Pigs invasion and the 1962 Cuban missile quarantine until now. That is obviously lacking. Nor has there been any recent 1949 Geneva Conventions Common Article 2 event initiating a U.S.-Cuba IAC (e.g., hostilities, declaration of war, or occupation). For instance, there is no information available to support characterization of the February 2026 speedboat incident as hostilities between Cuba and the United States in the Common Article 2 sense.
As to the second option, it is equally clear that the U.S. measures do not amount to a blockade that would trigger the applicability of LoNW rules on blockade. This is because (as noted above) the existing embargo on Cuba, whilst quite comprehensive, is a creature of U.S. domestic law, not international law. The fact that these embargoes have been primarily enforced by operation of U.S. financial, trade, and other jurisdictional arrangements surrounding sanctions, rather than in any military operations “at sea,” is an important indicator of their functional legal basis.
A claim as to the embargo’s legitimacy in LoNW could raise the interesting issue of “distant blockade” — the enforcement of a blockade by having the physical means to enforce (warships) held in latency rather than deployed on station. The classic, but legally ambiguous, case is the United Kingdom’s use of the threat of the Grand Fleet in situ at Scapa Flow as the enforcement mechanism for the blockade against Germany in World War I.
But in the Cuba case, sanctions rather than ships have been the tools of embargo enforcement. Indeed, the United States has sought to enforce the new oil-specific embargo against Cuba primarily through diplomatic and sanction pressures, which have forced the cancellation of voyages. A de facto surveillance perimeter appears to exist, with U.S. maritime patrols and uncrewed aerial vehicles (UAVs) monitoring tanker routes in the Caribbean, but it has not yet been accompanied by maritime interdiction actions explicitly directed at Cuba-bound traffic.
Finally, it might be argued that a “blockade” in the LoNW sense exists based on the interdictions of Venezuela-linked tankers. Those operations, so the argument would go, satisfy the effectiveness requirement for blockades vis-à-vis Cuba. In this regard, an oil tanker — the Anatoly Kolodkin — was allowed to enter a Cuban port, seemingly precluding characterization of the purported blockade as effective. However, the Administration has described this as a special concession. If there were a blockade of Cuba in force, allowing the Anatoly Kolodkin to dock in Cuba would arguably be compliant with the LoNW blockade rule that allows certain humanitarian cargoes through.
But there is not. As a legal proposition, treating the U.S. actions as a blockade of Cuba fails, for the presence of U.S. maritime forces and the interdictions in question are, in general, directly and publicly linked to the Venezuela sanctions, as subsequent forfeiture processes indicate. They are not directed at Cuba, thereby precluding their qualification as a U.S.-Cuba IAC under the law of armed conflict that would permit a LoNW blockade against that State. And because key elements necessary for a LoNW blockade are absent in respect of Cuba (because they are tied to Venezuela-related operations), the U.S. operations cannot qualify as a LoNW blockade that has itself triggered a U.S.-Cuba IAC.
Alternative Bases for the Embargo?
As we noted with respect to the Venezuela blockade, there is no U.N. Charter basis for the Cuba embargo. The Security Council has not adopted a Chapter VII mandate to authorize it. Indeed, insofar as U.N. General Assembly resolutions reflect the views of U.N. members, it is worth noting that the annual resolution calling for the end of the U.S. embargo against Cuba has been adopted for 33 consecutive years.
Further, there is no identifiable law of the sea basis for the complete suppression of oil trading with Cuba by means of interdiction. Absent flag State consent or a Security Council mandate, the legal bases for such actions are circumscribed in the U.N. Convention on the Law of the Sea and customary international law (see analyses of these authorities in the Venezuela context here, here, and here). Beyond the consent of the flag-State or master, no recognized exception to the exclusive jurisdiction of the flag State is relevant in this case.
Use of Force
Article 2(4) of the U.N. Charter prohibits “the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations,” a prohibition that undoubtedly reflects customary international law (Paramilitary Activities, ¶ 190). Might the U.S. measures have crossed the use of force line?
To date, the United States has not used physical force against Cuba or any entity associated with Cuba, such as a Cuban-flagged vessel; physical force directed at another State is generally considered a use of force in the Article 2(4) sense. In this regard, we note that blockading another State’s ports or coast is also considered a use of force. Indeed, it is an “act of aggression” according to the U.N. General Assembly’s Definition of Aggression Resolution, which is a well-accepted catalog of acts that can qualify as uses of force (art. 3(c)). However, as explained above, the current U.S. actions do not qualify as a blockade.
The question, therefore, is whether the economic measures employed by the United States nevertheless qualify as a use of force. According to the prevailing view among States and scholars, economic coercion does not constitute a use of force. As the late Yoram Dinstein explained in his classic work, War, Aggression and Self-Defence (6th ed., page 90)
when studied in context, the term ‘force’ in Article 2(4) must denote violence. It does not matter what specific means — kinetic or electronic — are used to bring it about, but the end result must be that violence occurs or is threatened. Therefore, psychological or economic pressure (e.g., in the form of economic boycott) as such does not come within the purview of Article 2(4), unless coupled with the use or at least the threat of force. Pressure of this sort amounts to a breach of other norms of international law, but it does not run afoul of this provision of the Charter.
The conclusion finds strong support in the Charter’s travaux (see analysis, pages 905-06). Moreover, economic coercion is conspicuously absent in the Definition of Aggression Resolution. And the Charter’s structure reinforces the conclusion. Article 41 separately contemplates Security Council measures “not involving the use of armed force,” including economic measures, while Article 42 addresses measures involving armed force. That division supports the mainstream view that Article 2(4)’s reference to “force” is armed force, not economic pressure as such.
It is true that, as noted by the late Oscar Schachter long ago, “Governments represented in the United Nations have from time to time sought to give the prohibition in article 2(4) this wider meaning, particularly to include economic measures that were said to be coercive” (page 1624). On the attendant facts, such an argument would enjoy more traction than it usually would, for the consequences of the U.S. measures include, inter alia, nationwide blackouts, disruptions to hospital services, and threats to the food supply.
We do not support such a characterization, as the mainstream view reflects settled doctrine and appropriately balances policy concerns about stretching the use of force threshold too far. However, if the U.S. actions were to directly cause deaths or serious illness in Cuba, the case for treating them as a use of force would, in our estimation, become stronger, although even then, we note that there is little State practice of treating economic measures having severe consequences as uses of force.
And should such consequences occur, there would be no legal justification for having taken the action. First, the Security Council has not authorized the U.S. measures under Chapter VII of the U.N. Charter. More to the point, there has been no Cuban “armed attack” triggering the right of self-defense under Article 51 of the Charter and customary international law. Cuba’s alignment with Russia, its hosting of foreign intelligence facilities that the U.S. government has described as targeting the United States, its alleged support for U.S.-designated terrorist organizations, and its provision of security personnel to the Maduro government do not, individually or collectively, constitute armed attacks on the United States.
Threat of the Use of Force
This leaves the question of the threat of the use of force in violation of Article 2(4). To violate the prohibition, three elements must be satisfied: the threat must be (i) communicated effectively to the target State; (ii) credible, given the threatening State’s capacity and demonstrated willingness to act; and (iii) involve a use of force for which there is no legal basis, most importantly, no colorable self-defense claim (see this discussion of threats).
Trump administration officials have expressly and impliedly threatened to use force against Cuba. In addition to the statements cited above, in March, Trump said he would have the “honor” of “taking Cuba.” He continued, “Whether I free it, take it, I think I can do anything I want with it…. They’re a very weakened nation right now.” Later that month, the president said, “I built this great military. I said, ‘You’ll never have to use it.’ But sometimes you have to use it. And Cuba is next by the way.” And this month, Trump warned, “We may stop by Cuba after we finish with this,” referring to the conflict with Iran. These and other statements by administration officials satisfy the first element.
Considering the uses of force against Venezuela and Iran, the threats are certainly credible, a fact not lost on Cuban authorities. Just over a week ago, Cuban President Miguel Díaz-Canel observed, referring to a speech by Castro the day before the Bay of Pigs attack:
“The moment is extremely challenging and calls upon us once again, as on April 16, 1961, to be ready to confront serious threats, including military aggression. We do not want it, but it is our duty to prepare to avoid it and, if it becomes inevitable, to defeat it.”
And it must be recalled that the United States openly seeks dominance over the Western Hemisphere. Indeed, the 2025 National Security Strategy makes this desire a U.S. policy objective: “After years of neglect, the United States will reassert and enforce the Monroe Doctrine to restore American preeminence in the Western Hemisphere, and to protect our homeland and our access to key geographies throughout the region.”
And so too is the third element. As explained, there is no basis for the use of force against Cuba. The Trump administration’s threats — as they did vis-à-vis Venezuela, Denmark, and Iran — are threats of force for which no valid jus ad bellum justification exists, and therefore are a violation of international law.
The Prohibition on Coercive Intervention
A further issue is whether the U.S. actions constitute an intervention into the internal or external affairs of another State, in violation of the well-established prohibition on such interventions under international law. A rule of customary international law, the International Court of Justice (ICJ) explained, “The principle of non-intervention involves the right of every sovereign State to conduct its affairs without outside interference” (Paramilitary Activities, ¶ 202). To qualify, the action must 1) coercively intrude into 2) the domaine réservé.
With respect to the latter, the ICJ has explained, “A prohibited intervention must accordingly be one bearing on matters in which each State is permitted, by the principle of State sovereignty to decide freely,” giving the example of “the choice of a political, economic, social and cultural system, and the formulation of foreign policy” (¶ 205). And as to the former, it noted that coercion occurs when such choices are no longer “free ones” (id.). Importantly, coercion must be distinguished from mere influence, which affects choice but leaves the target State with choice, even if a bad choice.
Regime change is, of course, the paradigmatic example of interference with the choice of a political system. And EO 14380, on its face, concerned Cuba’s domaine réservé, as modifications or suspensions were allowed if Cuba or an affected country aligned itself sufficiently with the United States on national security and foreign policy matters.
The question, therefore, is whether the U.S. actions are merely influential or coercive. This is a threshold that is somewhat unsettled, with the contested issue being economic coercion. We take the prevailing view that economic measures, such as sanctions, do not rise to the level of coercion in this area of law. For instance, States are not obligated in international law to trade with other States.
But there are economic measures… and there are economic measures. The U.S. campaign operates through three interlocking mechanisms. First, following the capture of Maduro, the United States directed the new Venezuelan transitional authority to cut off oil shipments to Cuba, that State’s primary energy supply for more than two decades. Second, Executive Order 14380 threatened economy-wide tariff surcharges against any third State that supplied oil to Cuba, a threat that, as intended, disrupted sovereign trade decisions and, therefore, the oil supply chain, even though no tariffs were ultimately imposed before the mechanism was revoked. Third, U.S. maritime operations in the Caribbean, including vessel seizures and drone surveillance of tanker routes, have created a de facto enforcement perimeter around the island.
The cumulative effect is designed to render the maintenance of Cuba’s existing political and economic system untenable. A near total reduction in fuel supply over a period of months, accompanied by repeated collapses of the national power grid, paralysis of transportation, disruption of hospital services, and impairment of agricultural productivity, cannot be equated with the incidental side effects of targeted financial measures. It is the mechanism itself — the systematic denial of oil — that distinguishes this campaign from ordinary “retorsion,” the legal term of art denoting lawful but unfriendly measures that States may direct at one another. In our view, a campaign calibrated to deprive an entire State of its primary energy source falls squarely within the category of coercion regarding matters the ICJ placed at the core of the prohibition on intervention.
The strongest response available to the United States for its oil denial campaign is the taking of countermeasures under the law of state responsibility. However, any such justification would fail.
Under the customary international law of State responsibility, which is generally reflected in the International Law Commission’s Articles on the Responsibility of States for Internationally Wrongful Acts, an “injured State” may take, otherwise unlawful countermeasures against a “responsible” State for the purpose of compelling the latter to desist in its own internationally wrongful act (arts. 22, 49-54).
This framework does not fit the current situation, for Cuba’s actions must be internationally wrongful with respect to the United States. A major concern expressed in EO 14380 is the fact that adversaries use Cuba as a situs for intelligence activity targeting the United States. However, despite occasional claims to the contrary, espionage and other forms of intelligence gathering are not unlawful under international law, a fact evidenced by U.S. intelligence activities targeting its adversaries on a massive scale. Cuba’s activities may be a security concern, but they violate no legal obligation owed to the United States. Nor would hosting foreign military forces, another point raised in the EO, so long as those forces did not themselves engage in activities against the United States that violated international law. It also alleges that Cuba violates international human rights law, a contention with which we agree. But such violations breach no legal obligation owed to the United States.
We note that certain human rights that Cuba may be violating are erga omnes obligations owed to the international community as a whole (Barcelona Traction, ¶¶ 33–34). As such, all States may invoke their breach (Articles on State Responsibility, art. 48). However, the clearly prevailing view, with which we agree, is that the right to take countermeasures is reserved exclusively to the “injured State” (art. 42; art. 54, commentary ¶ 6).
The sole plausible basis for finding an internationally wrongful act against the United States would be the support for terrorism alleged in the EO 14380. However, for the terrorism to be wrongful, it would have to be directed at the United States, and the actions of the terrorists would have to be attributable under the law of State Responsibility. And to be attributable, the terrorists would have to have been “acting on the instructions of, or under the direction or control of, [Cuba] in carrying out the conduct” (Articles of State Responsibility, art. 8).
This is a factual determination, although, at least from open-source material, it does not appear that Cuba has that level of control over any of the groups. But even if that were the case, justification of the U.S. action as countermeasures would fail due to the categorical prohibition on measures that “affect obligations for the protection of fundamental human rights” (art. 50(1)(b). This is so regardless of the wrong to which the purported countermeasure was responding. Many of the consequences of the oil denial campaign, such as nationwide grid collapse, disruption of medical care, and threats to food and water supply, fall squarely within the conduct that Article 50(1)(b) was designed to prohibit. Therefore, it cannot be characterized as a countermeasure.
Conclusion
Labels matter, but they do not answer legal questions. The U.S. campaign against Cuba is not a law of naval warfare blockade. It is a coercive oil-denial campaign (embargo) conducted through domestic sanctions authorities, tariff threats, diplomatic pressure, and the spillover effects of related maritime enforcement against other targets of sanctions. That distinction keeps the analysis outside the LoNW blockade rules and places it under the U.N. Charter, the law of the sea, the prohibition on intervention, and the law of State responsibility.
On present facts, the embargo does not amount to a use of force, although if the humanitarian situation in Cuba worsens, a stronger case can be made that it does. However, official threats concerning Cuba can reasonably be characterized as violating the prohibition on the threat of the use of force. Even more clearly, the effort to force regime change by depriving Cuba of the fuel necessary to sustain daily life violates the prohibition on intervention into the internal affairs of another State.
None of this denies that the United States may pursue legitimate security and human rights objectives regarding Cuba. It may criticize, sanction, restrict trade, and use diplomacy to oppose conduct it regards as threatening or unlawful. But international law limits the means by which even legitimate objectives may be pursued. A campaign that seeks to force a turnover in government by cutting off an island State’s essential fuel supply threatens — and, in important respects, crosses over — those boundaries.
