Bad news for oil markets and world trade: the US says it will blockade Iran again and charge every ship passing through the Strait of Hormuz a 20% cut of its cargo.

• Trump declared the US the "guardian" of the Strait of Hormuz and said all cargo shipped through it must pay a 20% fee.
• The reasoning: the US spends a fortune keeping its Navy and bases in the region, so other countries should pay for the protection.
• This comes after a claimed Iran deal fell apart, with the US now threatening to "hit them very hard" and run the strait itself.
• Oil prices are set to climb, since a 20% toll adds roughly $15 to every barrel and grows as oil gets more expensive.
• Dubai is already planning a new port to bypass the strait entirely, a sign other countries are moving on rather than pay the toll.

Outlook: Expect higher oil prices, angry allies, and more countries building ways around the strait; markets are falling on the uncertainty.