Yemeni coast guard officer shakes hands with members of the Houthi movement during withdrawal from Saleef port in Hodeidah province, Yemen May 11, 2019. Yemen's Houthi movement on Saturday started withdrawing forces from Saleef port in Hodeidah under a U.N.-sponsored deal stalled for months, a Reuters witness said, reviving hopes for peace efforts to end the four-year war. REUTERS/Abduljabbar Zeyad

Members of the Houthi movement are seen during withdrawal from Saleef port in Hodeidah province, Yemen May 11, 2019. Picture taken May 11, 2019. Yemen's Houthi movement on Saturday started withdrawing forces from Saleef port in Hodeidah under a U.N.-sponsored deal stalled for months, a Reuters witness said, reviving hopes for peace efforts to end the four-year war. REUTERS/Abduljabbar Zeyad

Members of the Houthi movement are seen during withdrawal from Saleef port in Hodeidah province, Yemen May 11, 2019. Yemen's Houthi movement on Saturday started withdrawing forces from Saleef port in Hodeidah under a U.N.-sponsored deal stalled for months, a Reuters witness said, reviving hopes for peace efforts to end the four-year war. REUTERS/Abduljabbar Zeyad

Yemen's Houthi movement forces are seen during withdrawal from Saleef port in Hodeidah province, Yemen May 11, 2019. Yemen's Houthi movement on Saturday started withdrawing forces from Saleef port in Hodeidah under a U.N.-sponsored deal stalled for months, a Reuters witness said, reviving hopes for peace efforts to end the four-year war. REUTERS/Abduljabbar Zeyad

Members of the Houthi movement ride in the back of a vehicle during withdrawal from Saleef port in Hodeidah province, Yemen May 11, 2019. Yemen's Houthi movement on Saturday started withdrawing forces from Saleef port in Hodeidah under a U.N.-sponsored deal stalled for months, a Reuters witness said, reviving hopes for peace efforts to end the four-year war. REUTERS/Abduljabbar Zeyad

Yemen's Houthi movement forces ride in the back of a vehicle during withdrawal from Saleef port in Hodeidah province, Yemen May 11, 2019. Picture taken May 11, 2019. Yemen's Houthi movement on Saturday started withdrawing forces from Saleef port in Hodeidah under a U.N.-sponsored deal stalled for months, a Reuters witness said, reviving hopes for peace efforts to end the four-year war. REUTERS/Abduljabbar Zeyad