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 waterway sealed until Washington unconditionally lifts its naval blockade of Iranian ports. The declaration, broadcast by Iran’s state-run IRIB broadcaster, marks a dramatic escalation in the rapidly deteriorating confrontation between Tehran and Washington over control of one of the world’s most strategically vital maritime chokepoints.
“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 Corps further issued an unambiguous warning that any vessel attempting to approach the waterway would be treated as acting in “cooperation with the enemy” — a designation that carries the explicit threat of military strikes.
The closure follows a blockade imposed by the United States Navy on 13 April, which has halted all maritime traffic entering and exiting Iranian ports on both sides of the Strait of Hormuz. The strategic significance of this waterway cannot be overstated: the Strait serves as the transit corridor for approximately 20 per cent of the world’s oil, petroleum products, and liquefied natural gas supplies, making any prolonged closure a matter of acute concern for global energy markets and the economies of nations across the Global South that depend on uninterrupted hydrocarbon flows.
Washington has maintained that non-Iranian vessels retain the right to transit the Strait of Hormuz freely, provided they do not remit any toll payments to Tehran. Iranian authorities, for their part, have not formally announced the imposition of such a toll, though discussions regarding the measure have been reported within official Iranian circles. The IRGC’s framing of the US blockade as a “violation of the ceasefire regime” suggests that a prior diplomatic understanding — the precise terms of which remain publicly unspecified — has been breached in Tehran’s assessment, providing the legal and political justification for Saturday’s closure declaration.
The closure of the Strait of Hormuz, even temporarily, represents one of the most consequential acts of maritime sovereignty asserted by any nation in recent decades. For the Global South — whose energy security, shipping lanes, and economic stability are intimately tied to the free flow of Gulf hydrocarbons — the standoff between Washington and Tehran carries profound and immediate implications. Oil-importing nations across Asia, Africa, and Latin America now face the prospect of supply disruptions and price shocks as the crisis unfolds.
Iranian Vice President statements earlier on Saturday had already signalled Tehran’s resolve, with officials indicating that control over the Hormuz passage would be “secured one way or another.” The IRGC’s formal closure announcement has now translated that political resolve into an operational military posture, with naval forces positioned to enforce the restriction.
The international community, shipping operators, and energy markets are closely monitoring developments as both sides show no immediate signs of de-escalation. The coming hours are expected to be decisive in determining whether diplomatic channels can be reopened or whether the confrontation deepens into a full-scale maritime crisis with global repercussions.
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