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, carried by Iran’s state broadcaster IRIB, marks one of the most consequential escalations in the Persian Gulf in recent memory, with immediate implications 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. The command further issued an unambiguous warning that any vessel attempting to approach the waterway would be subject to military strikes, with such an approach characterised as “cooperation with the enemy” — a direct reference to the United States.
The closure follows the US Navy’s imposition of a comprehensive maritime blockade on 13 April, which has targeted all traffic entering and exiting Iranian ports on both sides of the Strait of Hormuz. The strategic waterway is of extraordinary global significance, serving as the transit corridor for approximately 20 per cent of the world’s oil, petroleum products, and liquefied natural gas supplies. Any sustained disruption to passage through the Strait is widely regarded by energy analysts as capable of triggering severe shocks to international commodity markets.
Washington has sought to frame its blockade in narrow terms, asserting that non-Iranian vessels remain free to transit the Strait of Hormuz provided they refrain from paying any toll to Tehran. Iranian authorities have not formally announced the introduction of such a toll, though discussions regarding the measure have been reported at senior governmental levels. Tehran, for its part, has characterised the US naval action as a violation of an existing ceasefire arrangement, lending the closure the character of a retaliatory and legally grounded sovereign response rather than an act of unilateral aggression.
The IRGC’s declaration places third-party shipping companies, energy importers across Asia, Europe, and beyond, as well as regional governments, in an acutely precarious position. With both the US blockade and Iran’s counter-closure now simultaneously in effect, the Strait of Hormuz — the world’s most critical maritime chokepoint — has effectively become a theatre of active geopolitical confrontation. Iran’s Vice President had earlier signalled that control of the Hormuz passage would be “secured one way or another,” a statement that now appears to have been a direct precursor to Saturday’s formal closure order.
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