ISTANBUL — President Trump says that the U.S. will not allow Iranian ships to move through the Strait of Hormuz.

In a post online, Trump said, “We are reinstating THE IRANIAN BLOCKADE, so named because it is only stopping Iran’s ships or customers from entering or leaving.”

Trump said other countries will be able to move through the waterway, but that the U.S. would charge a 20% toll on cargo. He said the toll was reimbursement for doing “the job of providing safety and security to this very volatile section of the World.”

The U.S. previously has argued against any tolls or fees being enforced on ships moving through the strait.

Iranian leaders have been defiant that Iran controls the Strait of Hormuz.

Trump’s latest move comes after the U.S. and Iran exchanged fire for the third weekend in a row, raising the specter of a return to all-out war after a shaky ceasefire took effect in June.

This is a developing story, which will be updated.