Yemen’s civil war has intensified after the Iran-backed Houthi movement seized as much as 130 kilometers of Red Sea coastline, including the port of Mokha and the island of Perim. The advance gives the group significant control over the Bab al-Mandab Strait, a chokepoint for global shipping, and has renewed concern about oil-supply disruptions after six months of war between the US, Israel and Iran curtailed shipping through the Strait of Hormuz. Oil prices have risen on fears of broader economic disruption. The escalation followed the collapse of a four-year informal ceasefire, with more than 120,000 people displaced and hundreds reportedly killed. Saudi Arabia, which backs Yemen’s internationally-recognised government, has responded with air strikes, while the Houthis have attacked south-western Saudi Arabia, Saudi-linked commercial vessels, airports, oil facilities and tankers. The group says it is retaliating for a years-long Saudi blockade and an air strike on Sanaa airport, while insisting it does not threaten international shipping beyond Saudi-linked vessels. The Houthis, formally known as Ansar Allah, emerged in the 1990s and are led de facto by Abdul Malik al-Houthi. They control between one-quarter and one-third of Yemen’s territory but 70-80% of its population, or about 30 million people. Saudi Arabia and Western powers accuse Iran of supplying weapons in violation of a UN arms embargo, while Iran denies providing arms and says it offers only political support. The conflict risks drawing Western powers back into the war, although President Trump declined to strike the Houthis after they agreed not to target US targets. The UK agreed to deploy a military aircraft to help refuel Saudi fighter jets for what it called purely defensive missions.