On December 6, 2017, the U.S. President, Donald Trump, officially proclaimed Jerusalem as the capital of Israel. He also expressed the commitment of his administration to move its embassy from Tel Aviv to Jerusalem, a move which disturbed many Muslims around the world. Several countries in Europe expressed their reservations about Trump's proclamation. For Trump it was simply a matter of keeping his electoral promise.1
Trump's move was based on a controversial regulation of Jerusalem Embassy Act of 1995.2 The U.S. Congress adopted the Jerusalem Embassy Act in October 1995,3 which recognized Jerusalem as the capital of the state of Israel and acknowledged that it has been administered as a unified city implying the Israeli control. While not mentioning the disputed status of the city of Jerusalem, the Act set the deadline for moving the U.S. embassy there as May 31, 1999. Since 1998, all U.S. presidents opted to use their power to defer the act in order to avoid provoking the already enflamed Palestinian-Israeli conflict.
Source: Insight Turkey