The disputes, particularly over oil revenue, have led to severe economic problems in both Sudan and South Sudan, but the south, which had its first anniversary last month, is in a more precarious situation as it is more heavily dependent on outside assistance.
A senior U.S. official speaking on condition of anonymity because he wasn't authorized to discuss the matter publicly said she would express concern about a "lack of movement" in resolving the situation but also reaffirm America's strong support for South Sudan. The U.S. was instrumental in helping to negotiate the 2005 peace deal and the official said Washington is "heavily invested" in its success.
