The horrifying reports of the massacre of hundreds of Sudanese civilians after the Darfur city of El Fasher was captured by the rebel Rapid Support Forces (RSF) last week were the latest chapter in a brutal conflict that has killed more than 150,000 people over the past two and a half years.

But while the war in Sudan has most often been portrayed as an internal conflict between two warring generals, the murky involvement of several foreign powers makes the conflict far more complex – and deadly.

Much is at stake. “Whoever controls Sudan is in a position to have influence in the broader region, in the Horn of Africa, as well as sub-Saharan Africa,” said Charles Ray, a retired US diplomat who served as the US Ambassador to Cambodia and Zimbabwe and is now chair of the Africa Program at the Foreign Policy Research Institute.