The U.S. ambassador to the United Nations said there\'s reason to be hopeful that Sudanese leaders can find ways to settle their differences. A deal brokered while U.S. Secretary of State Hillary Clinton was visiting the region resolved an oil dispute between the Sudanese and South Sudanese governments. U.S. Sen. John Kerry, D-Mass., chairman of the Senate Foreign Relations Committee, said several \"contentious issues\" remained unresolved, however. A 2005 peace agreement secured South Sudan\'s independence last year. Ethnic tensions, border conflicts and skirmishes over oil revenue, however, have threatened the peace. U.S. Ambassador to the United Nations Susan Rice said it was \"vitally important\" that both sides work to settle their differences. She cautioned about moving forward with too much confidence, however. \"I think the reality is we have seen agreements in the past that have been signed on paper and never implemented on the ground,\" she said. Both parties, however, recognize that the African Union, the U.N. Security Council and other mediators are \"dead serious\" about pressing both governments to find a solution. While there may be \"consequences\" for non-compliance, she said, \"there is reason to be hopeful\" that both sides would find a way to settle their differences peacefully.