Iran has rejected Saudi accusations that it is behind a surge in Houthi attacks, after two missiles struck the airport in Aden, the interim capital of Yemen's internationally recognised government, late on Friday. The Houthis (an Iran-aligned armed movement that controls much of northern Yemen) claimed the strike, which was the second on the airport in under two weeks, and have launched more than 20 attacks on Saudi airports and energy sites since early October. The escalation adds pressure on Saudi Arabia, the world's top oil exporter, at a time when energy markets are already strained by Iran's closure of the Strait of Hormuz, while Tehran says it is ready to mediate.