Addis Ababa - Outgoing African Union Commission chairperson Nkosazana Dlamini-Zuma has slammed US President Donald Trump for the second time. This time she said his travel ban on seven Muslim-majority countries could herald "turbulent times" for Africa.In her last opening address to the African Union’s heads of state summit on Monday, Dlamini-Zuma told leaders: "We are entering very turbulent times.""The very country to which many of our people were taken as slaves during the transatlantic slave trade has now decided to ban refugees from some of our countries. What do we do about this? Indeed, this is one of the greatest challenges to our unity and solidarity," she said.Libya, Somalia and Sudan are the African countries affected by the ban. Dlamini-Zuma last Tuesday also expressed concern about Trump's presidency, saying it could affect the global advances made in the fight for gender equality as well as combatting climate change.A US diplomat stationed in Addis Ababa, however, said Dlamini-Zuma wrote them a "friendly" letter saying she looked forward to working with Trump. In the letter she also formally acknowledged former president Barack Obama as the first US president to visit the African Union.African leaders fear that Trump's policy of "America first" will mean less aid and assistance to countries on the African continent.