For critics of US President Donald Trump, escalating tensions between two long-standing American allies, Egypt and Ethiopia, over a mega dam on a tributary of the River Nile marks the biggest diplomatic failure of his administration in Africa. Mr Trump said last week that Egypt might “blow up” the Ethiopian-built dam, despite boasting in January that he deserved a Nobel Peace Prize because he had “made a deal”. “I saved a big war. I’ve saved a couple of them,” he said, shortly after Ethiopia’s Prime Minister Abi Ahmed was awarded the prize. Mr Trump’s comments were vague, but seemed to be a reference to his intervention – at the request of Egypt’s President Abdel Fattah al-Sisi, whom he once reportedly called his “favourite dictator” – to resolve the dispute over the Grand Ethiopian Renaissance Dam (Gerd). Egypt sees the dam as an “existential threat” to its survival, a concern shared, albeit to a lesser extent, by Sudan. Ethiopia, on the other hand, regards the dam as vital for its energy needs. Kenya-based Horn of Africa security analyst Rashid Abdi said US mediation over the dam had worsened tensions between Egypt and Ethiopia.