Over the last month, the world has witnessed a series of tit-for-tat maneuvers involving Iran, the United States and the United Kingdom. Sitting amidst the strategic and political stakes are complex questions of international law. Claims of ‘state piracy’ and proposing convoys in the Strait of Hormuz now appear to be contributing to the tension rather than facilitating the resolution of competing claims.
Most recently, Iran has seized the Stena Impero, a British-flagged commercial tanker, as well as a US drone and boarded but released a Liberian-flagged, British owned vessel. The United States has accused Iran of attacks against tankers and destroyed an Iranian drone. The United Kingdom seized an Iranian vessel off Gibraltar. Britain’s response to the seizure of the Stena Impero has been to denounce the act as ‘state piracy’ and it is now calling for the establishment of European-led convoys to protect commercial shipping.
Each of these incidents highlight tensions in the law of the sea, a field of international law that is highly dependent on reciprocity and mutual respect for the rules-based system so that core maritime interests are protected. A difficulty in applying the law of the sea to these incidents is that two of the protagonists, Iran and the United States, are not parties to the principal treaty, the United Nations Convention on the Law of the Sea. Iran is a signatory, which means it should act in good faith not to defeat the aims and purposes of the treaty in accordance with article 18 of the Vienna Convention on the Law of Treaties. However, Iran is not legally bound to act consistently with its terms. The United States takes the view that the key rules of the Convention at stake here reflect customary international law and therefore bind all states as a legal matter.
For the United States and the United Kingdom what matters here is the freedom of navigation. This centuries-old principle allows the movement of both commercial and military vessels across the world’s oceans. This freedom of the high seas facilitates the movement of over 90% of the world’s trade; it is of critical economic importance.
For this reason, navigational rights also exist through the narrowest straits. When moving through straits, like the Strait of Hormuz, the freedom of navigation is recast as innocent passage or transit passage. Transit passage applies when waters that are otherwise subject to the sovereignty of the coastal state connect the high seas and are used for international navigation. Vessels exercising these rights of passage are expected to proceed through continuously and expeditiously and in doing so will be free of interference from the coastal state.
The Strait of Hormuz connects the Persian Gulf and the Gulf of Oman and falls within the territorial waters of Iran and Oman. A fifth of the world’s oil is shipped through this strait. When Iran signed the Convention, it declared that the regime of transit passage would apply to the Strait of Hormuz in relation to parties to that treaty. This position should benefit the United Kingdom, but not the United States.
While commercial shipping should be able to move freely through the Strait of Hormuz on this basis, the situation is complicated because the same navigational rights do not apply within the internal waters of a state. Internal waters are those closely connected to the coastal state’s land and are usually demarcated through the drawing of baselines on navigational charts.
The law of the sea sets out criteria for drawing baselines and one of the difficulties in the Strait of Hormuz is that the United States disagrees with how Iran has drawn its baselines. The United States considers that Iran is claiming far too much as internal waters and reducing the maritime area that is otherwise available for transit passage rights.
Iran has claimed that the Stena Impero violated international maritime rules. Iran has alleged the Stena Impero did not assist a small fishing vessel after colliding with it, contrary to international regulations on collision. States bordering straits are allowed to regulate maritime traffic and ensure the safety of navigation, but they are not to deny, hamper or impair the right of transit passage.
In response, UK Foreign Secretary Jeremy Hunt characterised Iran’s actions as ‘state piracy’. This label carries no legal meaning. The international law definition of piracy refers to persons on oneship boarding another ship on the high seas through an act of violence or depredation for private, often financial, incentives.
This seizure has not occurred on the high seas and the involvement of state actors mean it was not for private ends. While legally nonsensical, the advantage would seem to be that it prevents the United Kingdom from ratcheting up the legal stakes by calling Iran’s actions an unlawful use of force or an armed attack.
Nonetheless, the further response of the United Kingdom in contemplating convoys does legally inflame the situation. Mr. Hunt advocated for ‘European-led maritime protection mission(s) to support safe passage of both crew and cargo’. It is not entirely clear how this initiative will differ from the United States’ proposed Operation Sentinel, although the United Kingdom claims it is not joining the United States’ maximum pressure policy.
Providing protection for international shipping was previously deployed in the Persian Gulf during the Iran-Iraq war when the United States and other neutral states provided naval escorts to merchant vessels. The doctrine of convoy, which was disputed at the time by both Iran and Iraq, is part of the law of naval warfare. That is, it is usually used during times of war.
More recently, naval vessels have been used to protect international commercial shipping from piracy in the Gulf of Aden and out into the Indian Ocean. Stopping pirates is one thing. The British Royal Navy engaging directly with the Iranian Revolutionary Guard? That is much more like armed conflict.
Australia should consider carefully its own participation in these operations when the legal significance of both US and British responses have raised the stakes yet again. Tactics reminiscent of what was known as the Tanker War are unlikely to work.
Australia is right to support the freedom of navigation, which is clearly at stake in Iran’s actions. Iran’s response to the seizure of its own vessel also indicates the importance of navigational rights to Iran. Rather than risking military encounters, it would be better to resolve the current seizures and focus on this shared interest in navigation through these waters.
Professor Natalie Klein is a Professor at UNSW Sydney’s Faculty of Law, Australia. She was previously at Macquarie University where she served as Dean of Macquarie Law School between 2011 and 2017, as well as Acting Head of the Department for Policing, Intelligence and Counter-Terrorism at Macquarie in 2013-2014. Professor Klein teaches and researches in different areas of international law, with a focus on law of the sea and international dispute settlement.