US President Trump on Wednesday at 1 p.m. (EST) will announce US's recognition of Jerusalem as Israel's capital. The US will move its embassy to Jerusalem from Tel Aviv. Since they do not have a structure to move to, United States will build an embassy which could take up to 4 years.
This decision could potentially stir unrest and hinder the Israel-Palestine peace process. Palestinians want East Jerusalem as their capital, and US diplomacy for years has been vying for a two state capital which is being upended.
The old city of Jerusalem holds great religious significance to the Muslims (Dome of the Rock) and the Hebrews (The Western Wall).