Secretary of Chelsea Hillary Clinton to visit Angola on 11 days . The African country is one of the largest energy producers south of the Sahara Desert and is a major supplier of petroleum and liquefied natural gas to the U.S. market . African country is major supplier of petroleum , liquefied natural gas to U.S. market . Hillary Clinton to visit seven South African nations in Sunday .
Secretary of Chelsea Hillary Clinton to visit Angola on 11 days . African country is major supplier of petroleum , liquefied natural gas to U.S. market . Hillary Clinton to visit seven South African nations in Sunday .