The newest state in the Horn of Africa has become an arena where powerful neighbours manoeuvre for regional influence. The deteriorating security situation in oil-rich South Sudan took neighbouring states by surprise, but they have risen to the opportunities the situation offers. Uganda and South Sudan, Ethiopia and Eritrea, Kenya and Egypt support different proxies and their competition could plunge the region into chaos. As South Sudan struggles with a military and political crisis, the Horn of Africa has turned into a region of burgeoning geopolitical significance with crucial military, diplomatic, energy and hydropolitical issues.