If that happens - the Iranians are vowing to stop all oil exports from the Gulf, including from the number one supplier Saudi Arabia.
Foreign ministers from France, Germany, Britain, China and Russia are expected to meet Iranian diplomats on Friday.
In Vienna, they'll be discussing how to salvage the 2015 Iran nuclear deal which Trump withdrew from two months ago.
Presenter: Adrian Finighan | Guests: Mamdouh Salameh - Author: 'Over a Barrel' and oil & energy expert; Hamed Mousavi - Professor of Political Science, University of Tehran; Sami Hamdi - Editor, International Interest magazine