Egypt putting pressure on Ethiopia because Ethiopia controls the source of the Nile. The Ethiopians are building a huge dam that has the potential to completely disrupt waterflow to both Nile tributaries - the White Nile & Blue Nile. I think, I read somewhere that White & Blue are 80% of the Nile water flow. I can see Egypt going to war with Ethiopia over this. There is no Egypt without the Nile.
It's the Blue Nile. Egypt has no ability to strike and invade Ethiopia. This is really just some posturing by al-Sisi.