U.N. Security Council votes to bolster peacekeeping force in South Sudan To reach those totals, the resolution authorizes U.N. Secretary General Ban Ki-moon to temporarily transfer some of the 16,200 U.N. and African Union troops currently deployed to Darfur, in western Sudan, as well as troops deployed in smaller contingents in Liberia, Ivory Coast and Congo. At the same time, Ban has already reached out to the African Union and countries such as Ethiopia and Rwanda, which are traditional suppliers of peacekeeping troops on the continent. Appeals have also gone out to Pakistan, Bangladesh and Nepal. The council condemned the fighting in South Sudan and demanded "an immediate cessation of hostilities and the immediate opening of a dialogue." The action came after U.N. High Commissioner for Human Rights Navi Pillay said at least one mass grave has been discovered in South Sudan amid the escalating violence. "Mass extrajudicial killings, the targeting of individuals on the basis of their ethnicity and arbitrary detentions have been documented in recent days," Pillay said in a statement. "We have discovered a mass grave in Bentiu, in Unity State, and there are reportedly at least two other mass graves" near Juba, South Sudan's capital and largest city. Expressing concern about worsening human rights violations in the 2 1/2-year-old country over the past 10 days, Pillay called on leaders on both sides of the conflict to protect civilians and curb ethnic violence. She spoke a day after about 150 U.S. Marines, along with transport and refueling aircraft, arrived in Djibouti on the Horn of Africa to aid in possible evacuation and protection missions in South Sudan. The fighting pits troops loyal to President Salva Kiir, an ethnic Dinka, against followers of his former vice president, Riek Machar, an ethnic Nuer who was fired in July. Machar loyalists have seized control of the northern town of Bentiu, the capital of the oil-producing Unity state. On Monday, clashes erupted in another oil-producing region, Upper Nile state, adding to the growing instability. A spokeswoman for the U.N. human rights office, Ravina Shamdasani, said officials counted 14 bodies in a mass grave in Bentiu and 20 more at a nearby river, the Associated Press reported. She said the victims were reportedly members of Kiir's Sudan People's Liberation Army, the South Sudan government force, and were among 75 ethnic Dinka who were reported to the United Nations as "unaccounted for and feared dead." Pillay said she was worried about the safety of detainees being held in unknown locations, including several hundred civilians who were reportedly arrested during house-to-house searches and from various hotels in Juba. She said hundreds of members of the South Sudan National Police Service were also reportedly ordered disarmed and arrested from police stations across Juba. "There is a palpable fear among civilians of both Dinka and Nuer backgrounds that they will be killed on the basis of their ethnicity," Pillay said. She warned political and military leaders that they can be held responsible for human rights violations committed by their followers. More than 40,000 internally displaced people have already sought refuge in the compounds of the U.N. Mission in South Sudan, Pillay said, and the total displaced population is expected to be much higher, with people reportedly seeking shelter in churches and other locations. The newly deployed U.S. Marines are part of a Marine Air-Ground Task Force based in Morón, Spain. Defense officials emphasized that they have not yet been ordered to South Sudan but were on standby in case they need to be deployed. Four U.S. troops were wounded Saturday when an air mission to evacuate American citizens was fired upon in the city of Bor. That mission was aborted, leading to a letter to Congress on Sunday from President Obama saying that he "may take further action to support the security of U.S. citizens, personnel and property, including our Embassy, in South Sudan." The arrival of the Marines on the African continent coincided with a decision by Ban to ask members of the United Nations for additional troops to bolster a 7,000-strong peacekeeping mission in South Sudan, the U.N. Mission in South Sudan (UNMISS). "The situation is of mounting urgency," Ban said at U.N. headquarters in New York on Monday morning. I am especially worried by reports of ethnically targeted killings. Asked Monday whether the United States would assist in transporting the new U.N. peacekeeping troops, U.S. Ambassador to the U.N. Samantha Power said there had not yet been a specific request. But she cited the "overwhelming consensus, overwhelming desire to move quickly" amid "very significant alarm" at the worsening situation on the ground. The U.S. Defense Department has deployed 150 Marines from a rapid response team based in Spain, along with three V-22 Osprey aircraft and three C-130 refuelling tankers, to Djibouti for possible use in evacuation and protection missions in South Sudan. The draft Security Council resolution calls for "an immediate cessation of hostilities and the immediate opening of a dialogue" in South Sudan and says that "attacks on U.N. personnel will not be tolerated." UNMISS is one of three U.N. forces in South Sudan and its neighbor, Sudan, from which it became independent in 2011. Nearly 20,000 U.N. and African Union troops are in violence-plagued Darfur, a region on Sudan's western border. A 4,000-strong U.N. Interim Security Force is based in Abyei, the oil-rich territory along the border of the two countries. Although fighting between the north and the south has gone on for years, and led to a U.S.-backed peace treaty that in 2005 ended Africa's longest-running civil war, the outbreak of internal hostilities in South Sudan has disrupted one of the largest U.S. aid programs in Africa. The United States has long been deeply engaged in the region, supporting the separation of the two states with massive attention and assistance. The Obama administration requested nearly $400 million in assistance for humanitarian and governance programs in South Sudan in its 2014 budget. Thousands of civilians, including an unknown number of Americans and other expatriates, most of them working with aid organizations, have sought refuge inside U.N. bases that, in some cases, have been surrounded by hostile forces. About 380 Americans have been evacuated. The Obama administration's special envoy to Sudan and South Sudan, Donald Booth, visited Juba on Monday. He said he had "a frank and open discussion with President Kiir." Kiir "committed to me that he was ready to begin talks with Machar to end the crisis without preconditions," the envoy said. But even as Kiir promised a rapprochement, he told South Sudan's parliament that government troops would be dispatched to retake Bor, the capital of central Jonglei state, which is under the control of Machar loyalists. The impending offensive threatens to worsen the political crisis and the humanitarian situation. Ragavan reported from Juba.