Tehran, 18 April 2026 — Iran has formally closed the Strait of Hormuz effective Saturday evening, the Islamic Revolutionary Guard Corps (IRGC) Navy Command announced, declaring the closure will remain in force until the United States unconditionally lifts its naval blockade of Iranian ports. The announcement, broadcast by Iran’s state-run IRIB network, marks one of the most consequential escalations in the Persian Gulf in recent memory, with immediate ramifications for global energy markets.
“As a result of the violation of the ceasefire regime, the Strait of Hormuz will be closed from the evening of today [Saturday], until the US lifts the naval blockade,” the IRGC Navy stated in its official communiqué. The command further issued an unambiguous warning that any vessel attempting to approach the waterway would be subject to military strikes, characterising such transit as “cooperation with the enemy” — a direct reference to the United States.
The closure follows a naval blockade imposed by the US Navy on 13 April, which has effectively halted all maritime traffic entering and exiting Iranian ports on both sides of the Strait of Hormuz. Washington has maintained that non-Iranian vessels retain the right of free passage through the Strait, provided they refrain from paying any toll to Tehran. Iranian authorities, while not having formally announced the imposition of such a toll, had previously discussed the possibility as a sovereign revenue mechanism.
The strategic weight of this confrontation cannot be overstated. The Strait of Hormuz serves as the transit corridor for approximately 20 per cent of the world’s oil, petroleum products, and liquefied natural gas supplies. Its closure, even temporarily, is widely regarded by energy analysts as a trigger for severe disruption to global supply chains, price volatility, and potential shortages across importing nations — particularly those in Asia, Europe, and the broader Global South.
Iran’s Vice President had earlier signalled the government’s resolve, stating that control of the Hormuz would be “secured one way or another,” underscoring that Tehran views the US blockade as a fundamental violation of its sovereignty and of previously established ceasefire arrangements. The IRGC’s Saturday declaration transforms that political posture into an active military and maritime policy.
The unfolding crisis places third-party nations — including major oil importers across Asia and Africa — in an acutely precarious position, as shipping lanes that underpin their energy security are now contested by two nuclear-capable powers. The international community has yet to issue a coordinated response, and no emergency session of the United Nations Security Council has been convened as of the time of publication.
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