[I hope the Ethiopians didn’t get any help from the Chinese to build this dam.]
The Ethiopians had better have good air defenses around the dam. Because, given the importance of the Nile’s water flow to the country’s agricultural sector, I see the Egyptians doing something like this:
https://www.youtube.com/watch?v=btnDa1azF2c
https://www.usaid.gov/egypt/agriculture-and-food-security
[Agriculture is a major component of the Egyptian economy, contributing 14.5 percent of the country’s gross domestic product. The agricultural sector accounts for 28 percent of all jobs, and over 55 percent of employment in Upper Egypt is agriculture-related.]
The water rights to the Colorado River are quite complicated, but somehow Colorado, Utah, Nevada, Arizona, and California despite all of the dams get enough for now.
If we get another 50- or 100-year drought then we could be seeing similar antagonisms here in the States.