Yemen's Iran-aligned Houthi movement has warned shipping companies that tankers using Saudi Arabian ports risk being attacked, moving quickly to enforce a naval blockade it announced a day earlier. The threat, coming alongside Iran's separate moves against shipping in the strait of Hormuz, could hit Saudi oil exports that had until now escaped disruption from the region's months-long conflict, further deepening a fast-escalating crisis.

Two oil tankers that had loaded Saudi crude bound for China and India reversed course on Tuesday, heading towards the Suez Canal instead of passing the Houthi-controlled coast at the mouth of the Red Sea; the Houthis claimed six vessels in total had diverted. In an email sent on Monday, the group told shipping firms not to load or unload cargo at Saudi ports, warning such activity could see them targeted "in any location". Donald Trump said the US would "take care of business" if the Houthis followed through, while diplomats worked to salvage a collapsed Iran-US interim deal amid a tenth day of renewed strikes between the two countries. The Bab el-Mandeb strait, controlled by the Houthis, carries around 7% of global maritime traffic, and experts warned any vessel calling at Saudi ports or carrying Saudi oil could now be at risk.