Iran's Islamic Revolutionary Guard Corps has declared that the Strait of Hormuz will remain closed to maritime traffic until the United States ceases what it describes as acts of aggression.
The military branch also warned that other oil transit routes could face similar closures if Washington does not change its stance.
The statement comes amid heightened tensions in the region, following reports that the US and Iran had previously reached a deal to halt hostilities and reopen the strait.
The IRGC's renewed threat suggests that any diplomatic progress may be fragile or contested by hardline factions within Iran's military establishment.
For global markets, the Strait of Hormuz is a critical artery for oil and gas shipments, with roughly a fifth of the world's oil consumption passing through the narrow waterway daily.
Any sustained closure would likely trigger sharp spikes in Brent crude prices and disrupt supply chains for energy-importing nations across Asia and Europe.