After reaching an impasse in ceasefire negotiations, the United States has implemented a total blockade of Iranian ports, a response to Iran’s successful closure of the Strait of Hormuz.
While this action from Washington may seem to echo Iran’s tactics, it is fundamentally aimed at exerting pressure on energy-importing nations that Iran considers to be “friendly,” allowing their vessels to navigate the strait.
Both the US and Iranian approaches have sparked disputes regarding their legality, raising issues related to “territorial waters” versus “international waters.” This article examines the international legal framework governing maritime navigation and military engagement, particularly in light of the ongoing strategies from both nations.
The Strait of Hormuz serves as a crucial bargaining chip for Iran. Since the onset of the US-Israel alliance’s military actions on February 28, Iran has maintained significant control over the strait by targeting ships and deploying mines, leading to one of the most severe energy crises globally, given that this narrow channel accounts for approximately 20% of the world’s energy trade.
Tehran has proposed a 10-point plan to legitimize its dominance over the strait, requesting US acknowledgment of its sovereignty over this critical passage.
In March, an Iranian parliamentary commission approved proposals to levy tolls on vessels transiting the strait. Reports indicate that Tehran has also suggested sharing the tolls with Oman and asserted via social media that the Strait of Hormuz is not part of international waters but rather under Iran’s territorial jurisdiction, along with that of Oman.
Although naval warfare laws provide some legitimacy to the actions of laying mines and imposing blockades, Iran is reportedly capitalizing on its strategic position by imposing a fee of $2 million on each vessel navigating this chokepoint, redirecting maritime traffic around Iran’s Larak Island.
This alternative route, claimed to be free of mines according to a map released by the Islamic Revolutionary Guard Corps (IRGC), lies within Iran’s territorial waters. Diplomatic sources have dubbed this arrangement the “Ayatoll booth.”
Furthermore, a report from the Financial Times indicates that Iran is considering implementing a fee of $1 per barrel in cryptocurrency, aiming to use the proceeds as reparations for the conflict.
Iran’s approach, however, contravenes a comprehensive array of international maritime delimitation laws, placing the country in a legally ambiguous position concerning the laws of naval warfare.
Unlike the Suez Canal, navigation through the Strait of Hormuz is regulated by the United Nations Convention on the Law of the Sea (UNCLOS), which guarantees free and unimpeded navigation for all vessels traveling this route.
Although the Strait of Hormuz is situated within the territorial waters of both countries, the shipping lanes designated for westbound and eastbound traffic—under the International Maritime Organization’s (IMO) Traffic Separation Scheme (TSS)—are entirely within Omani territorial waters. This implies that Iran is attempting to impose fees in areas administered by Oman.
Notably, the maritime boundaries were established through a treaty between Iran and Oman in July 1974, with both countries having joined the IMO in June 1958 and July 1974, respectively.
The 1969 Vienna Convention on the Law of Treaties (VCLT), which is often referred to as the foundational treaty of treaties, stipulates that a nation that has signed but not ratified a treaty is obligated to avoid actions that would undermine the treaty’s purpose.
Consequently, although Iran has not ratified UNCLOS, it should refrain from actions that contradict its fundamental principles.
Both Iran and the US have signed but not ratified the Vienna Convention, yet the rules outlined in the convention are still viewed as binding for both parties.
In terms of the US strategy and its legal implications, Washington’s NATO allies, including the UK, France, and Germany, have expressed clear disapproval of the conflict in West Asia. Additionally, Italy and Spain have denied the US access to a crucial airbase and restricted its military use of their airspace, respectively.
Amidst this situation, Iran has permitted ships from US allies—such as France, Japan, and South Korea—as well as vessels from India, China, Russia, Pakistan, and Iraq to pass through the Strait of Hormuz. This tactic allows Iran to mitigate potential global backlash while deepening the divide between the US and its traditional allies.
With its own blockade in place, the US aims to shift the dynamics in its favor. President Donald Trump has stated that the US Navy will “intercept every vessel in International Waters that has paid a toll to Iran.”
The US Central Command has indicated that the blockade will be enforced “impartially against vessels of all nations entering or departing Iranian ports and coastal areas,” covering all Iranian ports in the Persian Gulf and the Gulf of Oman.
While Trump maintains that these measures will ultimately facilitate “safe passage on the high seas,” the act of blocking vessels linked to Iran could also infringe upon the principle of freedom of navigation, similar to Iran’s tactics.
It is noteworthy that the US has not ratified UNCLOS either, suggesting a potential future scenario where both nations find themselves in violation of a legal framework to which neither has formally committed.
