U.S. Secretary of State Hillary Clinton departs this week on a trip that will take her both to Africa’s newest nation, South Sudan, and on a visit to the continent’s elder statesman, 94-year-old anti-apartheid icon Nelson Mandela.While Clinton’s public focus will be on Africa’s democratic achievements and economic potential, the trip also underscores U.S. security ties in the face of an array of growing threats --from Islamist extremists to narcotics cartels."The security threats are becoming much more visible and in some ways dangerous than they were before,” said Jennifer Cooke, the head of the Africa program at the Center for Strategic and International Studies in Washington."There are big global issues on the table, and the U.S. does not have the kind of finances available to mount splashy new economic initiatives in Africa.”Clinton’s trip -- potentially her last as America’s top diplomat -- begins on Tuesday in Senegal, and continues on to South Sudan, where she will be the most senior U.S. official to visit since the country declared independence in July 2011. Further stops include Uganda, Kenya, Malawi and South Africa, the State Department said.Clinton is expected to highlight U.S. programs on development, education and HIV/AIDS -- long the backbone of U.S. engagement with Africa -- as well as U.S. economic interest in a continent whose rich resources and enviable growth rates have drawn rival suitors including China and India.She will also likely emphasize projects for women and girls, one of her central themes in a job she says she will leave in January even if President Barack Obama is elected to a second term.