U.S. Secretary of State Hillary Clinton has arrived in South Sudan, where she is expected to push for compromise between the world's newest country and Sudan.

Clinton is meeting Friday with South Sudan President Salva Kiir in Juba during the brief visit.

Sudan and South Sudan failed to meet a United Nations August 2 deadline to settle differences on citizenship, oil revenue, and border demarcation that remain unresolved 13 months after the two nations split. The diplomatic failure could expose both nations to economic sanctions.

A U.S. State Department official traveling with Clinton on her multi-nation African tour said the bitter divisions over territory and oil threaten to wreck the economies of both nations.

The sides clashed along their border in April, raising fears of all-out war.

In interviews with VOA on Thursday, both sides accused the other of slowing progress.

Sudan's foreign affairs undersecretary, Ramatallah Osman, said Khartoum is dissatisfied with a proposed buffer zone along the border to prevent further fighting.

South Sudan's minister of information, Barnaba Benjamin Marial, said Sudan refuses to compromise.

Also Friday, Clinton meets in Uganda with President Yoweri Museveni. Clinton will use the talks to discuss Uganda's role as a key U.S. partner in regional security, as well as to encourage stronger democratic institutions and human rights.