Yemen has been mired in civil war for more than three years.
Forces loyal to the internationally recognized government of Abdrabu Mansur Hadi, and supported by the Arab coalition, have been battling the Houthi rebels, an Iranian-backed and armed militia.
UN Security Council Resolution 2216 officially recognizes Hadi as the country's president. It also calls for the Houthis to return Sanaa, which they captured in 2014, and demands the Houthis stop using Yemen as a base to attack neighbouring countries.
Neither has happened.