The United Nations said on Friday it had sent helicopters to rescue personnel from a base in South Sudan that came under lethal attack as a political crisis worsened significantly and President Obama warned that the world’s youngest country “stands at the precipice.” The number of civilians seeking refuge in the United Nations’ other facilities there exceeded 30,000 and diplomats expressed fears about the potential for a civil war. Britain, which began evacuating its nationals on Thursday, said Friday that it would send a second airplane to Juba, the capital. “We strongly advise all British nationals in South Sudan to leave the country if they can do so safely,” the Foreign Office said, adding that it might become more difficult to escape if the situation worsened further. The United States suspended operations at its embassy in Juba this week and offered similar advice to Americans. On its […]