The shells started landing inside Hussein Ali Wuhaish’s refugee camp days after the Biden administration ended U.S. support for a Saudi-led coalition fighting in Yemen and took steps to lift sanctions on northern rebels. The rebels, known as Houthis, seemingly emboldened by the American pivot, had intensified their offensive in strategic Marib province, one of the few safe harbors in the war. Now Wuhaish and his family, who fled to Marib in 2017, were once again on the run.

“I could hear the screams and the crying of my neighbors’ children, as my wife and I tried to calm our own children,” said Wuhaish, 38, a doctor and father of five. “We realized that we were again not safe.” “So as the sounds of the fighting got closer, we fled for our lives.”

The military escalation in Marib, the last northern stronghold of the internationally recognized Yemeni government, threatens to displace hundreds of thousands of Yemenis, many of whom have already fled violence multiple times. That would significantly worsen a humanitarian crisis already described by the United Nations as the world’s most severe, say U.S. and U.N. officials and aid workers.