A new front is opening as Yemen's Houthi rebels attack Saudi Arabia's oil exports and threaten a key shipping lane — bad for global energy and for anyone who buys fuel.

• The Houthis are hitting Saudi oil tankers and refineries and have declared a blockade on Saudi, Israeli, and US shipping.
• A strike forced Saudi Arabia to shut down its Jazan refinery, pulling 400,000 barrels a day of oil offline.
• The rebels now threaten to charge tolls on ships passing the Bab al-Mandeb strait, one of the world's busiest — a mob-style shakedown like Iran is running at Hormuz.
• With Hormuz already choked, losing this lane forces oil ships on a much longer route around Africa, raising costs worldwide.
• Saudi Arabia is rallying a 50-country coalition to keep the lane open, and may hand the lead to the US as its navy stretches thin.

Outlook: A full-blown Saudi-Houthi war looks likely, and combined with the Hormuz crisis it could hit global energy and prices hard.