Can Iran Close the Strait of Hormuz?

International Law International Studies Reasoned Comments
Listen to this article

By Ahmed E Souaiaia*

Since the Trump administration withdrew from the Iran Deal and re-imposed and imposed sanctions on Iran, Iranian leaders indicated that they will close the Strait of Hormuz if they are unable to sell their oil. In the last few months, a number of incidents had occurred with the potential for impacting the flow of oil through the Strait. On Thursday, Iranian authorities said that they shot down a US spy drone over its airspace. Hours later, US military confirmed the downing of the drone, with two corrections: The model of the drone and the location of drone when it was shot down. The former fact (or non-fact) is irrelevant legally, the latter is important. US military said that the drone was shot down while flying in international space.




Both sides agree that the incident took place in the Strait of Hormuz. If the shooting down of the drone took place in the narrowest area, US claim that its drone was flying in international waters would be false because, at that point, there is no international space. The space is either under Iranian sovereignty or Omani sovereignty

It is likely, therefore, that the incident took place on either sides of the Strait, in which case, there are international waters and sovereign waters belonging to Iran, Oman, and UAE. In this case, US and Iran will be under pressure to produce evidence about the whereabouts of the drone at the moment it was shot down. The evidence can be in the form of GPS records, satellite tracks, and/or location of the debris of the downed drone.

Given these escalations, it is also important to understand the legal regimes that govern passage through narrow waterways in general and the Strait in particular.

Since the narrowest point of the Strait of Hormuz is twenty-one nautical miles, all vessels passing through the Strait must traverse the territorial waters of Iran or Oman. Therefore, the rights of passage for foreign vessels under international law is subject to either the rules of non-suspendable innocent passage or transit passage. Generally, such passage is governed by the United Nations Convention on the Law of the Sea, UNCLOS, which entered into force November 16, 1994. (

When signing UNCLOS, Iran stipulated that it would apply the transit passage regime only to those states that ratified the convention. For other states, like the United States, Iran would apply the provisions of the 1958 Geneva Convention (

Applicable to this situation, and according to UNCLOS Article 39,

ships engaged in transit passage must proceed without delay; refrain from activities other than those incident to their normal modes of continuous and expeditious transit, unless rendered necessary by force majeure; refrain from any threat or use of force against the sovereignty, territorial integrity, or political independence of states bordering the strait; and refrain from acting otherwise in violation of the principles of international law embodied in the Charter of the United Nations.

What is significant here is that the drone that was shot down was a military asset, not a commercial vessel. Should war breakout between the US and Iran, Iran can then suspend passage for all US military assets through the Straight and remain within the exercise of its right. It may not be necessarily the case if Iran were to close the Straight before commercial vessels. This explains why the US is not eager to start an open war with Iran without UNSC or US Congress authorization. Moreover, Iranian leaders have warned regional countries, that, in case of war with the US, if US bases within their territories were to be used in military attacks, Iran will not hesitate to retaliate against such neighboring countries. Such a warning puts Qatar, Bahrain, UAE, and even Oman (which recently signed a military deal to allow some of its ports to be used by US military) on notice. In other words, war between Iran and US cannot be limited to these two countries, and importantly, a “strike” or violation of Iranian territories Iran warned that it will interpret as an act of war, and war in that region carries huge economic, political, legal, and security risks regionally and globally.

* Prof. SOUAIAIA is a member of the faculty at the University of Iowa with joint appointment in International Studies, Religious Studies, History, and College of Law. Opinions are the author’s, speaking on matters of public interest; not speaking for the university or any other organization with which he might be affiliated.



Leave a Reply

Your email address will not be published. Required fields are marked *