The U.N. Security Council is giving South Sudan one month to stop fighting and sign a peace deal or face an arms embargo and sanctions. The council passed a U.S.-sponsored resolution Thursday with the minimum nine votes needed for approval. Six members abstained. The resolution calls on Secretary-General Antonio Guterres to report back to the council on June 30. If there is still fighting and no “viable political agreement,” the council will consider an arms embargo and sanctions against six top South Sudanese officials. Ethnic fighting has raged in South Sudan since 2013 between forces loyal to President Salva Kiir and those backing his former vice president, Riek Machar. Tens of thousands have been killed and more than a million civilians have fled their homes. U.S. Ambassador to the U.N. Nikki Haley has called Kiir an “unfit partner” for peace. The relief group Doctors Without Borders reported Thursday on what it says …