The United Nations warns some 300,000 people have fled South Sudan this year amid renewed fighting that’s threatening to return the nation to civil war. The conflict grew worse after the arrest of First Vice President Riek Machar unraveled a fragile power-sharing agreement. South Sudan gained U.N. recognition as the world’s newest nation in 2011, but a civil war that erupted in 2013 led to an estimated 400,000 deaths.