The African Union this week called for a “regional protection force” to bolster a 12,000-strong U.N. peacekeeping mission in the East African country and separate warring parties. U.N. Secretary-General Ban Ki-moon has supported reinforcing the mission. The spokesman for South Sudan’s former rebel leader Riek Machar, now first vice president, says Machar has also called for a “third force” to secure the capital, Juba, after President Salva Kiir’s forces bombed his house during the fighting that raised fears of a return to civil war. The spokesman, James Gatdet Dak, said Machar fled Juba and will not return, despite Kiir’s invitation,...