The Saudi-led coalition fighting Iran-backed Houthi rebels in Yemen has teamed up with the World Health Organization to allow mercy flights to Cairo and Amman for seriously ill people unable to obtain treatment domestically. Starting on Monday, the UN-chartered flights are to depart from the international airport in the capital Sanaa. The facility is in Houthi hands but is blockaded by the coalition, which controls much of the country’s air space. A Houthi-operated television channel reported that Martin Griffiths, the UN special envoy to Yemen, had arrived in the country on Sunday to oversee the humanitarian flights, being called a “medical air bridge.” It is not entirely clear what led to the flights, although numerous press reports have noted that Riyadh is eager to reduce tensions with the Houthis since the rebels stepped up their anti-coalition attacks, including the use of rockets and drones aimed at Saudi airports and pipelines. The Houthis claimed responsibility for two major attacks from the air last September that temporarily paralyzed the Saudi oil industry, although Riyadh, Washington and several European countries have laid the blame on Iran’s doorstep.