Trump's renewed war with Iran is pushing oil and gas prices up, and a new Houthi blockade could make it much worse — bad news for the global economy and American drivers.

• Iran-backed Houthi rebels are blocking Saudi oil shipments through the Red Sea, cutting off one of the last workarounds to the closed Strait of Hormuz.
• Together these blockades could choke a big chunk of the world's oil supply.
• Gas hit $4 a gallon in the US and oil briefly topped $90 a barrel, and prices would be far higher if countries weren't draining their emergency oil reserves.
• Those emergency reserves are running low, and once they're gone there's no cushion left to keep prices down.
• There's no clear US strategy or exit plan, and experts say the war can only be ended through diplomacy, not force.

Outlook: If the war drags on and reserves keep shrinking, expect oil and gas prices to climb higher.