In a statement, the Islamic Revolutionary Guard Corps (IRGC) Navy warns that "no vessel is to move from its anchorage in the Persian Gulf or the Sea of Oman".
It says a number of vessels had passed through the strait under its management since last night, but that the waterway would shut again until the US stops its blockade of Iranian ports.
"Approaching the Strait of Hormuz will be considered co-operation with the enemy, and the offending vessel will be targeted," it adds.
IRGC saying it's closed. Trump saying it's open.
Who do you believe? Basically cancer vs AIDS.