Secretary of State John Kerry spoke on Saturday with South Sudanese President Salva Kiir to express "grave concern" about the conflict in South Sudan, including recent violence in Bentiu and Bor and the deliberate targeting of civilians by armed groups on both sides of the conflict, the State Department announced. Kerry welcomed the decision of the government of South Sudan to release the four senior political officials who had been in detention since December, said the statement released Saturday night by department spokeswoman Jen Psaki. Kerry urged Kiir to stop military offensives and adhere to the Cessation of Hostilities agreement, and noted U.S. demands that anti-government forces do the same, Psaki said. Both Kerry and Kiir expressed their support for the peace process led by the Intergovernmental Authority on Development (IGAD), she said. Kerry noted the important role played by the UN Mission in South Sudan (UNMISS), denounced recent attacks on UNMISS bases and personnel, and encouraged Kiir "to ensure full and unfettered access throughout South Sudan for UNMISS, the African Union Commission of Inquiry, and the IGAD Monitoring and Verification Mechanism," Psaki said