Iran-backed Houthi forces have taken Mayun Island, also known as Perim, at the narrowest point of the Bab el-Mandeb strait. The rocky volcanic island splits the channel into two shipping lanes between Yemen and the Horn of Africa.
Yemeni government officials said their forces withdrew from the island before Houthi fighters arrived by boat. The Houthis also hold the port city of Mocha and the island of Hanish, and now control most of Yemen's Red Sea coastline.
A new front in the Iran war
The advance is the group's largest territorial gain since a 2022 truce paused Yemen's civil war. It lands as the wider conflict between the United States and Iran grinds past the six-month mark, with the Strait of Hormuz already disrupted.
Bab el-Mandeb is only about 26 kilometres wide at its narrowest point. From the island, fighters can watch traffic in both directions and reach passing ships with shore-based guns. Analysts say that is a cheaper way to threaten shipping than the long-range anti-ship missiles the Houthis used in earlier campaigns.
Yemen's Saudi-backed government said it was defending freedom of navigation and condemned renewed Houthi attacks on Saudi Arabia. It asked for international support.
Oil, diesel and shipping costs
The timing is costly. Crude has traded above $100 a barrel, and diesel in the United States hit a record $6 a gallon in early September. Saudi Arabia shut down its East-West crude pipeline after several attacks, cutting a route that lets the kingdom move oil without passing Hormuz.
Shipping companies are weighing longer routes around the Cape of Good Hope. Those voyages add weeks, burn more fuel, and push up freight rates and insurance premiums.
United Nations officials warned that fighting between the Houthis and government forces ends a period of relative calm in Yemen and could displace more civilians.
What comes next
Military analysts expect the Houthis to use the island as a base for surveillance and small-boat operations rather than a fixed gun position, which would be easy to strike. Reports that Iran's Revolutionary Guard has sent advisers to support the campaign could not be independently confirmed.
For now the group controls a chokepoint it has spent years trying to reach, and it has new leverage over a waterway that carries a large share of global trade.