Yemenis hold up a Yemen's national flag during a rally in Sanaa, Yemen, on April 19, 2019. Thousands of Yemenis participated in a rally here on Friday against the continuing war and blockade imposed on Yemen. Yemeni political analysts said that U.S. President Donald Trump's veto over a congressional resolution that sought to end the U.S. involvement in Yemen proves the key American role in the war. (Xinhua/Mohammed Mohammed)