Addis Ababa has finally inaugurated the long-awaited and much-touted GERD—Africa's biggest dam—leaving Egypt and Sudan worried about the impact on their water supply downstream

As Addis Ababa stands to benefit from electricity and revenues, it reassures downstream nations that the $4bn river barrier is an opportunity, not a threat. That's not the view from Cairo.

An Egyptian minister warns Ethiopia it will "pay" for any harm done to Egypt's water security, stoking speculation that the long-running clash over its GERD dam will spark a water war

Cairo reserves its right under international charters to defend its water source as a matter of national security in the event of harm, raising the spectre of military conflict.