Addis Ababa (AFP) - Barack Obama will be the first-ever US president to address the African Union on Tuesday, in the culmination of a short tour of the region that has seen him focus on security and human rights.After visiting Kenya, the country of his father's birth, Obama is in the Ethiopian capital, the seat of the pan-African body, where he has already praised the country as a key partner in the war against Al-Qaeda-affiliated Shebab militants in Somalia."Part of the reasons we've seen this shrinkage of Shebab in East Africa is that we've had our regional teams," Obama said, referring to African Union and Somali government troops."We don't need to send our own Marines in to do the fighting: the Ethiopians are tough fighters," Obama said, adding: "We've got more work to do.