Secretary of State John Kerry says the United States supports African-led efforts to combat "the most deadly conflicts of the continent."
He said Thursday during his visit to Addis Ababa, that too many nations are at risk of descending into broad-based violence.
"It is clear that the unspeakable violence in the Central African Republic, the deliberate killing of civilians on both sides in South Sudan, both of those underscore the urgency of the work that we have to do together."
Kerry visited the African Union's headquarters in the Ethiopian capital for talks with officials on the C.A.R., where Muslims continue to flee their homes to escape attacks by Christian militia.
Earlier Thursday he met with the foreign ministers of Ethiopia, Uganda and Kenya to discuss the challenges of how to get South Sudan's warring sides to halt their months of deadly fighting. The top diplomats agreed that South Sudan needs a legitimate force to help stabilize the country.
The United States has already threatened travel and financial sanctions against those responsible for violence that has displaced more than a million people.
A senior State Department official has said Kerry planned to deliver "tough messages" for both the South Sudanese government and rebels during his visit to Africa this week.
Kerry is also due to meet with Somali President Hassan Sheikh Mohamud to discuss the fight against the al-Qaida-linked militant group al-Shabab.
On Saturday, the secretary travels to the Democratic Republic of Congo's capital to meet with President Joseph Kabila. The two will discuss recent security gains against rebel groups in volatile eastern Congo.
On Sunday, Kerry heads to Angola for a meeting with longtime President Jose Eduardo dos Santos. He returns to Washington on Monday.