In Yemen, the United Nations warned Thursday an epidemic of cholera could reach 300,000 cases by the end of August. U.N. Emergency Relief Coordinator Stephen O’Brien said the spread of the often-deadly disease was entirely preventable.

Stephen O’Brien: “This is because of conflict. It’s man-made. It’s very severe. The numbers are absolutely staggering. It’s getting worse. And the cholera element, in addition to all the lack of food, the lack of medical supplies for people, is of course—primarily, one has to put that at the door of all the parties to the conflict.”

The warnings over cholera came as the U.N.’s humanitarian coordinator called on a U.S.-backed, Saudi-led military coalition to halt airstrikes in Yemen, citing mounting civilian deaths and the June 19 targeting of the main water supply system in Dhamar City, which affected 1 million people.