The downing of a US Navy RQ-4 Global Hawk by Iran over the Strait of Hormuz has set the Middle-East and the world on edge. The ensuing political maelstrom is obscuring the legal rights and wrongs of this incident. As usual they are not clear cut but rather complicated.
The U.S. claims that the drone –which was on a surveillance mission– was shot down over “international waters” – about 21 nautical miles (nm) outside of Iran’s ‘legitimate’ 12 nm territorial sea in the southern Strait Of Hormuz. https://www.militarytimes.com/news/2019/06/20/pentagon-issues-map-depicting-us-drone-shot-over-international-waters/ Iran claims it was shot down in Iranian airspace. https://www.businessinsider.com/map-iran-vs-us-airspace-argument-drone-shooting-2019-6
A U.S. – issued map showing the location of the shoot-down is not much help in clarifying the issues because the U.S. and Iran have conflicting claims as to the status of the waters in and the airspace over that area.
First of all, legally there is no such thing as the US claimed “international waters”. For the Strait of Hormuz, there are internal waters landward of the baseline, territorial sea extending 12 nautical miles (nm) seaward of the baseline, and beyond that in the area in question a 200 nm Exclusive Economic Zone extending to the agreed boundary with Oman. According to the UN Convention the Law of the Sea (UNCLOS) each zone has its own rules governing navigation.
Iran and Oman have claims that together encompass the entire Strait of Hormuz in the area in question. However, the U.S., Iran and Oman have different interpretations of the international law regarding their maritime claims and the applicable navigation regime there. https://2009-2017.state.gov/documents/organization/58228.pdf Neither Iran nor the U.S. have ratified the UN Convention on the Law of the Sea (UNCLOS). Indeed, the U.S. remains the only maritime power outside it. However the U.S. claims that ‘most’ of UNCLOS is customary international law. As a non-party, Iran is arguably not bound by it.
UNCLOS allows a coastal state to draw straight baselines along an indented coastline and to claim a 12nm territorial sea from these baselines. Iran claims a straight baseline that enables a claim to a 12 nm territorial sea encompassing a portion of the Strait in that area. The U.S. does not recognize this straight baseline, arguing that Iran’s coast there is neither indented nor fringed with islands as required by UNCLOS. Thus the U.S. does not recognize the full extent of Iran’s claimed territorial sea in the Strait. But Oman,by formally agreeing to a continental shelf boundary there, apparently recognizes Iran’s baselines. https://2009-2017.state.gov/documents/organization/61448.pdf
The U.S. also claims that transit passage applies in the Strait. Iran claims a regime of innocent passage there. There are significant differences between the two regimes. Transit passage means freedom of navigation and over flight solely for the purpose of continuous and expeditious transit of the strait. It cannot be impeded, hampered or suspended.
Innocent passage is a more restrictive regime. Such passage cannot be prejudicial to the peace, good order, and security of the coastal State. If a warship or aircraft violates an innocent passage regime and refuses to comply, it can be requested to leave the territorial sea immediately. Of particular relevance here is that a warship or aircraft in innocent passage cannot undertake intelligence gathering.
Iran’s publicly declared position is that countries like the U.S. that are not parties to UNCLOS cannot avail themselves of a transit passage regime in the Strait. It instead claims that the innocent passage regime applies to such states’ vessels and aircraft moving through its territorial sea and further that passage of all warships through and aircraft over Iran’s territorial sea requires prior authorization. The latter provision is not consonant with UNCLOS. Oman – – a party to UNCLOS– apparently agrees with Iran by recognizing only innocent passage through the Strait for all countries and requiring prior permission for passage of warships.
Many developing countries would probably support Iran’s general argument that UNCLOS was negotiated as a package deal trading off provisions regarding preferential access and sharing of seabed resources beyond national jurisdiction for navigational liberties including transit passage and archipelagic sea lane passage for maritime powers. In particular, in negotiations, the U.S. agreed to a 12 nm territorial sea in exchange for the transit passage regime. Before UNCLOS there was no “transit passage regime.” The pre-existing regime was innocent passage in territorial seas and Iran apparently claims that is still applicable to the U.S. in the Strait of Hormuz.
Over flight of Iran’s territorial sea without its permission would be a violation of its sovereignty. But even if the drone was in transit passage, according to UNCLOS it must “refrain from any threat or use of force against the sovereignty, territorial integrity, or political independence of states bordering the strait.” Given the circumstances, spying on Iran’s military may well have been considered preparation for an attack. https://foreignpolicy.com/2019/06/21/trump-fearing-casualties-aborts-iran-strike-at-last-minute/
There are other relevant differences in the legal positions of the two. Even if the drone was beyond the claimed Iranian territorial sea, Iran prohibits military activities within its EEZ that are “inconsistent with [its] rights and interests”. Thus the over flight of a military surveillance drone would be prohibited. Of course the U.S. argues that this would be an abridgement of the freedom of navigation in the EEZ. This is what UNCLOS seems to say. But Iran is not alone in its interpretations and positions. Indeed, many countries, including in Asia, China, Indonesia, Malaysia, Thailand, Vietnam and Indonesia require permission for foreign warships to operate in their territorial seas. Some like India, Malaysia and Thailand—like Iran– have restrictions on military activities even in their 200 nm EEZs .
Of course these legal differences have all been overwhelmed by the political turmoil. But if and when the din dies down and cooler heads have time to analyze the legal situation, the U.S. and the world may come to realize that the legal issues are not ‘cut and dry’ and that both sides’ legal arguments have significant weaknesses.