Iran closes Strait of Hormuz; Gulf states enter the war

On 27 March 2026 the Islamic Revolutionary Guard Corps announced that no vessel travelling to or from the ports of the United States, Israel or their allies would be permitted through the Strait of Hormuz — the latest step in a month-long closure sequence that began with radio warnings to shipping within hours of the 28 February strikes (see US-Israeli strikes on Iran kill Khamenei; war begins), was formally confirmed by IRGC officials in early March (2 March in the Institute for the Study of War’s chronology; 4 March per the Congressional Research Service), and was reinforced by US intelligence reports of Iranian mine-laying on 10 March and Foreign Minister Abbas Araghchi’s 15 March statement that the strait was “open” but barred to US- and Israel-linked vessels.¹² The closure sits inside a widening war. On 11 March the UN Security Council adopted Resolution 2817 (2026) by a vote of 13-0 with China and Russia abstaining — tabled by Bahrain for the Gulf Cooperation Council states and Jordan with a record 135 co-sponsoring countries — condemning Iran’s “egregious attacks” on Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, the United Arab Emirates and Jordan, demanding immediate cessation, and condemning interference with navigation through the strait; Iran’s ambassador Amir Saeid Iravani said that “[t]oday’s action represents a blatant misuse of the Security Council mandate in pursuit of the political agendas of the certain members.”³⁴ On 8 March the Assembly of Experts, meeting in Qom with more than two-thirds of its 88 members attending, selected Mojtaba Khamenei — son of the Supreme Leader killed on 28 February — as Iran’s third Supreme Leader, with state media reporting approximately 85 percent of votes cast.⁵ The Gulf monarchies moved from targets to belligerents through March: Saudi Arabia expelled Iranian defense officials on 21 March, and its cabinet resolved on 26 March, in a statement carried by the Saudi Press Agency, to take all necessary measures to defend the kingdom’s security, territory, citizens and residents; the UAE foreign ministry on 18 March condemned “Continued Iranian Terrorist Attacks on the UAE,” and Foreign Minister Abdullah bin Zayed said days later that the UAE “will never be blackmailed by terrorists.”⁶⁷ Israel began ground operations in southern Lebanon on 16 March after destroying the Litani River bridges from 13 March, with Defense Minister Israel Katz saying the IDF would hold “a security zone inside Lebanon” up to the Litani.⁸ The United States began an aerial campaign against Iranian coastal targets on 19 March aimed at reopening the strait.⁹

1. The energy-market transmission is the war’s principal global economic channel. The International Energy Agency’s Oil Market Report of 12 March describes the closure as “the largest supply disruption in the history of the global oil market,” projecting a global supply drop of about 8 million barrels per day for March as Hormuz flows fell from roughly 20 million barrels per day toward a trickle; Brent crude crossed $100 per barrel on 12 March as the closure held, per contemporaneous S&P Global price reporting.¹⁰¹¹ Roughly a fifth of global oil supply and a substantial share of global liquefied-natural-gas exports transit the strait; the disruption propagates through fuel, fertiliser (via natural-gas feedstock), aviation and shipping- insurance costs.¹⁰

2. Resolution 2817’s legal weight runs against Iran’s conduct, not the underlying US-Israeli strikes: the Council’s operative condemnation reaches Iran’s attacks on the seven named Arab states and its interference with navigation, affirms the “inherent right of individual or collective self-defense” recognised by Article 51 of the UN Charter, and a rival Russian draft condemning the strikes failed 4-2-9.³⁴ Freedom of navigation through the strait operates under the transit-passage regime of Part III of the UN Convention on the Law of the Sea — which the United States treats as customary international law — and Iran’s closure to vessels of specified states is inconsistent with the non-suspendable character of transit passage under Article 44.¹²

3. The Gulf states’ entries into hostilities proceeded without declarations of war, through cabinet resolutions, base-access grants and air-defense integration; the pattern replicates the coalition structure of prior Gulf conflicts in which US Central Command operates from host- nation facilities under bilateral defense-cooperation agreements; the Emirates News Agency’s running interception series documented UAE air defenses engaging Iranian ballistic missiles and drones through March.¹³

4. The succession of Mojtaba Khamenei concentrates wartime authority in a leader elevated mid-conflict; dissent within the Assembly of Experts session was reported by the London-based opposition outlet Iran International (an outlet with a stated adversarial posture toward the Islamic Republic, disclosed accordingly).⁵¹⁴ The interim leadership council — President Pezeshkian, Chief Justice Mohseni-Eje’i and Guardian Council jurist Alireza Arafi, announced by Ali Larijani on 1 March — stood down on the announcement; Iranian military command continuity through the war runs through the General Staff and the IRGC under the new Supreme Leader’s formal command.⁵