What began as a civil war in 2015 between Yemen's government and Iranian-backed Houthi rebels has evolved into a brutal proxy conflict between Saudi Arabia and Iran, with U.S. involvement. Jane Ferguson updates us from Yemen on the war's terrible toll, and Nick Schifrin speaks with the Biden administration's envoy about the world's largest humanitarian crisis. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders