With thousands of frightened civilians seeking refuge at its peacekeeping bases in South Sudan, the United Nations is seeking a near doubling of the peacekeeping force in the strife-ridden African nation, two United Nations officials said. United Nations Secretary General Ban Ki-moon, who signaled the need for reinforcements, has not said publicly how many additional troops he is seeking to secure South Sudan, the world's youngest country. But one U.N. official, who asked not to be identified because he was discussing internal plans, said five additional battalions, two additional police units and attack helicopters were needed-an increase of 5,000 personnel. The United Nations currently has 7,633 military personnel and police in South Sudan.