On December 6, 2017, President Trump recognized Jerusalem as the capital of Israel and instructed the State Department to develop a plan to relocate the U.S. Embassy from Tel Aviv to Jerusalem. On December 21, 2017, two weeks later, the United Nations voted 128-9 (with 35 abstentions) to demand that the US rescind the declared move.
Oxford University Press has made available a number of free resources explaining the legal and historical background of the issue and providing an account of the governing law.