Legal Status of the Strait of Hormuz: Reviewing Iran’s Arguments Within the Framework of the Law of the Sea

The Strait of Hormuz is considered one of the world’s most critical maritime passages and has long been a focal point for governments and international actors. Its geopolitical significance is heightened by the fact that key shipping lanes lie within the territorial waters of Iran and Oman, placing it at the center of international legal discussions.

Amid the recent conflict, Iran moved to close the strait, a step that led to a sharp surge in global oil prices. The move prompted strong reactions from the President of the United States, who in recent days has sought to increase pressure on Tehran, including through discussions of a potential naval blockade.

The following outlines the key legal arguments cited by Iran:

First, Iran asserts its sovereign rights over its territorial waters, noting that the shipping routes within the strait fall entirely within the territorial seas of Iran and Oman, thereby granting it full authority to monitor and regulate passage.

Second, Iran has not ratified the 1982 United Nations Convention on the Law of the Sea (UNCLOS) and therefore does not consider itself bound by the “transit passage” regime, which allows unimpeded passage. Instead, it recognizes the more restrictive “innocent passage” regime under the 1958 Convention.

Third, under the innocent passage regime, Iran maintains it has the legal right to prevent the passage of vessels—particularly foreign warships—if it deems such movement harmful to its security, public order, or environment.

Fourth, under customary international law, Iran argues that if its national security is threatened or an attack occurs, it has the right to take defensive measures, including imposing navigational restrictions or temporarily closing the strait, in line with Article 51 of the UN Charter on self-defense.

Fifth, Iran may justify restricting access to the strait for specific countries as a countermeasure in response to what it considers unlawful sanctions or economic warfare, with the aim of compelling compliance with international obligations.

From Tehran’s perspective, national sovereignty over territorial waters takes precedence over the principle of freedom of navigation, particularly when such freedom is seen as undermining national security.

This approach reflects a combination of legal, security, and behavioral considerations recognized in international law, offering insight into Iran’s policies toward maritime traffic in this strategic waterway.