US President Donald Trump has announced that the US Navy and its allies are set to begin a blockade of the Strait of Hormuz, a key global oil shipping route.

"Effective immediately, the US Navy, the Finest in the World, will begin the process of BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz," The Caspian Post reports via Trump's message on Truth Social.

"At some point, we will reach an 'ALL BEING ALLOWED TO GO IN, ALL BEING ALLOWED TO GO OUT' basis, but Iran has not allowed that to happen by merely saying, 'There may be a mine out there somewhere,' that nobody knows about but them. THIS IS WORLD EXTORTION, and Leaders of Countries, especially the United States of America, will never be extorted. I have also instructed our Navy to seek and interdict every vessel in International Waters that has paid a toll to Iran. No one who pays an illegal toll will have safe passage on the high seas," Trump wrote.