Ambassador Cohen retired from the Department of State in 1993 after 38 years in the Foreign Service. His last position prior to retirement was Assistant Secretary of State for African Affairs in the first Bush Administration, during which he led US diplomatic interventions to resolve conflicts in Angola, Mozambique, Ethiopia, South Africa, Rwanda, the Sudan, Liberia, and Somalia. His book about these interventions, Intervening in Africa: Superpower Peacemaking in a Troubled Continent, won the American Academy of Diplomacy award for the best writing on diplomacy for the year 2000. Ambassador Cohen also served at American embassies in Uganda, Zimbabwe, Zambia, Zaire, and Senegal. He was the U.S. Ambassador to Senegal, with dual accreditation to Gambia, from 1977 to 1980. His Washington responsibilities included Director for Central Africa (1970-1974), Deputy Assistant Secretary for Intelligence and Research (1980-1984), and Senior Director for Africa at the National Security Council under President Reagan (1987-1989). Ambassador Cohen has worked under contract for the World Bank as Senior Advisor to the Global Coalition for Africa, and is currently President of Cohen and Woods International, which specializes in providing strategic advisory services to African governments, and business services to American companies engaged in trade and investment in Africa.

Ambassador Cohen described the problems posed for US national security interests by failed and unstable states in west, central and east Africa, with particular emphasis on the growing oil resources in west Africa, and the fight against terrorism on the eastern side of the continent.