Saudi Arabia's capital is meant to be one of the safest cities in the Middle East. On Saturday its main airport became a target. An attack on King Khalid International Airport in Riyadh killed at least 12 people and injured 309, the Saudi aviation authority said, including travellers from Bangladesh, Egypt, Jordan and the United States. Two days earlier, a missile strike there had killed three Saudis, one of them a pilot.
The likely attackers are the Houthis, a rebel movement backed by Iran that has ruled northern Yemen, Saudi Arabia's southern neighbour, since 2014. They claimed Thursday's strike and warned airlines to stay out of Saudi skies. Their missiles are a reply: on October 4, Yemen's Saudi-backed government launched an offensive to retake Houthi land, and Saudi-led jets have pounded the Houthi-held capital, Sanaa.
Asked whether America would join in, President Trump said: "We may. We're going to look at it." The UN's envoy for Yemen warned on Friday that the country has slid back into full-scale war.