Iran has long asserted that it can shut down the Strait of Hormuz. While the strait can't be "closed" in the traditional sense - like shutting a road - Iran could attempt to make the waterway too dangerous for commercial passage, effectively disrupting global shipping.

Pentagon officials are trying to prepare for all of the ways Iran could retaliate, as President Trump hints at what he might do.

Conflict between Israel and Iran has rekindled fears of a disruption to a narrow waterway key to the global economy. Skyscraper-sized tankers ferry roughly one-fifth of the world’s petroleum, as well as massive cargoes of natural gas,