ON DECEMBER 16, the United States (US) announced measures to block oil tankers entering and leaving Venezuela. The Trump administration alleges that Nicolás Maduro’s regime is engaged in drug trafficking and human trafficking. The U.S has expanded its naval presence in the region, ostensibly to interrupt the drug-smuggling boat.
According to TankerTrackers.com, more than 30 out of 80 vessels in Venezuelan waters or approaching Venezuela are under US sanctions. Over time, Trump's position has shifted from allegations of drug trafficking to claims that the Maduro government is using stolen oil to finance, what he terms, “drug terrorism” and human trafficking. In response, Venezuela has accused Washington of illegally expropriating its resources.
Considering Venezuela’s over-dependence on oil, the move carries far-reaching geopolitical implications. China has expressed its displeasure over the “unilateral bullying,” and Mexico has urged the United Nations to intervene to diffuse the tensions. Meanwhile, Deputy Chief of Staff Stephen Miller claimed in a post on Xt that the “tyrannical expropriation” by Venezuela amounted to “the largest recorded theft of American wealth and property.” Joaquin Castro, a Democrat from Texas, has termed these measures “an act of war.” Maduro has characterized the move as an attempt at regime change and an assertion of US control over Venezuelan territory and resources.
The total blockade by the US has left the scholars divided. According to NYU professor Ryan Goodman, “[t]here is no legal justification for a military blockade based on the grievances President Trump listed.” Writing for Just Security, Michael Schmitt and Rob McLaughlin argue that the US actions amount to a threat or use of armed force against oil tankers entering or leaving the territorial waters of Venezuela. They characterise blockade as the use of force, even prior to the actual use of force under Article 42 of the UN Charter, which expressly lists blockade as a coercive measure when non-forcible means have failed. They further argue that a blockade constitutes aggression within the meaning of United Nations General Assembly (UNGA) Resolution 3314.
This post contends that the act of blockade constitutes a violation of jus cogens or peremptory norm of international law, foreclosing any defence that the US might otherwise invoke. Such a violation would attract a higher degree of international responsibility under the law of State responsibility. The analysis is confined to jus ad bellum and does not probe into jus in bello.
Can blockade be an act of ‘aggression’?
The UN Charter does not authorise the unlawful use of force amounting to aggression. Rather, it vests the United Nations Security Council (UNSC) with authority to act against acts of aggression. Unlike other forms of use of force, aggression involves a particularly grave use of force. This distinction is found in the introductory paragraph of UNGA Resolution 3314, which characterizes aggression as the “most serious and dangerous form of the illegal use of force.”
Although the UNSC is competent to determine acts amounting to aggression beyond the non-exhaustive list provided in Article 3 of Resolution 3314, according to Mary Ellen O'Connell, this determination is often shaped by political considerations. Moreover, such determinations are vulnerable to a permanent member blocking a resolution on aggression. Article 3(c) expressly recognizes the blockade of a State's ports or coasts by the armed forces of another State as an act of aggression. Hence, the US blockade of ships entering and exiting Venezuela, while falling within this definition, is unlikely to attract formal UNSC censure given the possibility of a US veto.
Although the UNSC is competent to determine acts amounting to aggression beyond the non-exhaustive list provided in Article 3 of Resolution 3314, according to Mary Ellen O'Connell, this determination is often shaped by political considerations. Moreover, such determinations are vulnerable to a permanent member blocking a resolution on aggression.
A ‘peacetime blockade’ would qualify as a use of force even before any kinetic engagement with the ships, since Article 42 of the UN Charter provides for blockade as a measure which the UNSC can authorise when non-forceable actions fail. By implication, the unilateral imposition of a blockade, without the UNSC’s authorisation, breaches the prohibition on the use of force.
US officials have justified these actions on grounds of self-defence, a claim decipherable from Trump’s Truth Social post in the face of the drug threat. However, the shift in Trump’s position from interdicting drug-boats to claims over oil and other assets significantly weakens any claim of self-defence. Additionally, for invoking self-defence, the threshold of ‘armed attack’ is high; for instance, in the Nicaragua case, the ICJ categorised an armed attack as “the most grave” form of the use of force. On this reasoning, the US blockade would itself constitute a grave use of force, and potentially trigger Venezuela's right to self-defence. Finally, blockade cannot be justified on political, economic, military, or any other grounds, as affirmed by UNGA Resolution 3314.
Aggression as a violation of jus cogens
Jus cogens are peremptory norms of international law from which no derogation is permitted. In the hierarchy of norms, these are placed higher than treaties and customary international law. Scholars like Katie A. Johston and Corten identify prohibition of aggression as a jus cogens norm. Aggression is commonly used alongside the unlawful use of force, but its classification depends on the gravity and character of the force employed. In this context, in the Oil Platforms case, the ICJ did not exclude the possibility that the mining of a military vessel might be sufficient to bring into play the “inherent right of self-defence.”
Similarly, the blockade of the port of Mariupol and the Sea of Azov was regarded as constituting aggression; accordingly, scholars like James A. Green et al. regard the invasion of Ukraine as an act of aggression and a violation of jus cogens. Several authoritative international instruments identify aggression as a jus cogens norm. For instance, the International Law Commission’s (ILC) Draft Conclusion on Identification and Legal Consequences of Peremptory Norms of General International Law (jus cogens) in its non-exhaustive list locates prohibition on aggression as jus cogens; likewise, the ILC report on fragmentation identifies prohibition on aggression as the most frequently cited candidate for jus cogens status.
First, the supreme status of the prohibition of aggression as a jus cogens norm would entail an obligation erga omnes, wherein States not directly affected by the acts of the US could bring claims against it. This could be achieved through third-party countermeasures (sanctions) or by taking the US to the International Court of Justice. Furthermore, domestic jurisdictional claims would be strengthened if the prohibition on aggression were categorised as jus cogens, as States like Germany, Ukraine, and Switzerland have criminalised aggression in their domestic laws.
Second, States cannot be precluded from responsibility for jus cogens breaches. As Article 26 of the ILC Draft Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA) states: “Nothing in this chapter precludes the wrongfulness of any act of a State which is not in conformity with an obligation arising under a peremptory norm of general international law.” As Norman Finkelstein notes, “we’re upping the ante in order to try to get them to engage in an act of aggression that would then justify an act of self-defence on our part.” Further, the Pentagon officials view the blockade as a “quarantine,” a language employed during the 1962 Cuban Missile Crisis to cordon off weapon shipments from the Soviet Union. Such framing does not, however, alter the legal character of the act under international law. Hence, any justification, like self-defence, cannot be used to justify a blockade.
The ICJ’s position on self-defence for acts of aggression is evident in the Nicaragua case. There, the US attempted to justify collective self-defence for Nicaragua’s alleged aggression against El Salvador, Honduras, and Costa Rica; the argument was dismissed, as El Salvador’s request was not supported by an armed attack capable of triggering self-defence.
Jus cogens are peremptory norms of international law from which no derogation is permitted. In the hierarchy of norms, these are placed higher than treaties and customary international law.
Third, the jus cogens nature of the act means an additional layer of responsibility, beyond reparations. Third States have obligations to cooperate to end the serious breaches within the confines of the UN Charter; therefore, as confirmed in Legal Consequences of the Separation of the Chagos Archipelago from Mauritius, “all member States to co-operate with the United Nations to end the breach in question.” Accordingly, the UNGA could pass resolutions condemning US actions and recommend the UNSC to take coercive actions.
If this fails, as I have argued, suspension of the US could be contemplated from the United Nations. Moreover, third States are under an obligation not to assist in the commission of an unlawful act. Venezuelan Vice President Delcy Rodríguez has claimed that Trinidad and Tobago actively participated in the seizure of the US oil tankers off the country’s coast. If substantiated, facilitation of logistical access, such as permitting the use of airspace or airports, could amount to assistance in an unlawful act. Thus, third States, like Trinidad and Tobago, could be equally complicit in violating jus cogens.
The Trump administration has been repeatedly accused of breaching international law norms through unilateral economic sanctions, use of force in the Middle East, violations of non-refoulement, arbitrary detention, etc. Seen in this light, the recent actions are an extension of established US foreign policy practice. This is perhaps reflected in the US National Security Strategy which states: “The purpose of foreign policy is the protection of core national interests.” Nevertheless, the present blockade tests the outer limits of the international legal order and the continuing viability of the prohibition on the use of force.