U.S. Ambassador to the United Nations Nikki Haley (C, front) addresses a United Nations Security Council meeting on the humanitarian situation in Syria, at the UN headquarters in New York, March 27, 2018. UN Undersecretary-General for Humanitarian Affairs and Emergency Relief Coordinator Mark Lowcock said Tuesday that the last few months have been some of the worst for Syrian civilians as a result of ongoing violence. (Xinhua/Li Muzi)