Houthi forces have taken a key Red Sea island and a town on the strait, a bad sign for global shipping and oil routes and a defeat for Saudi-backed Yemeni forces.

• The island sits near the Bab el-Mandeb, the narrow passage where a tenth of world shipping and a lot of oil pass through every day.
• Saudi-backed Yemeni forces planned to fall back to a town on the strait — the Houthis took that too.
• The Houthis have momentum because the other side is tied to Saudi Arabia, which is widely hated in Yemen after a decade of war, and to Israel.
• The fighting restarted after Saudi forces bombed an airport as a Houthi delegation was returning home.
• The US already stepped back from its own campaign against the Houthis without beating them.

Outlook: With both sides of the strait slipping toward Houthi control, shipping risk and oil transit costs in the Red Sea are likely to rise further.