The United States says Ethiopia must, in the shortest possible time, sign a deal with Egypt and Sudan about a giant dam it is building on the River Nile.
Steven Mnuchin, the US treasury secretary, said the final testing and filling of the dam should not take place without an agreement.
Ethiopians have reacted angrily on social media, calling on Prime Minister Abiy Ahmed to resist US pressure.
Earlier this week Ethiopia failed to attend what was meant to be the final signing of an accord. Egypt and Sudan fear the $4bn (£3bn) dam will deprive their populations of water.
The Grand Renaissance Dam is at the heart of Ethiopia’s manufacturing and industrial dreams. When completed it is expected to be able to generate a massive 6,000 megawatts of electricity.