The White House on Tuesday confirmed that United States President Donald Trump will formally recognise Jerusalem as the Israeli Capital on Wednesday. This breaks away from years of policy and leaves room for uncertainty in West Asia.

Employees of the US government have been advised to avoid Jerusalem’s Old City and the West Bank until further notice, according to The Guardian. Security has been stepped up at US embassies across the world in anticipation of the backlash after the announcement is made.

For decades, the US has held that the status of Jerusalem should be decided through negotiations between Israel and Palestine, which wants East Jerusalem as the capital of the future state. A majority of countries do not recognise Israel’s claim to the whole of Jerusalem, where several Christian, Muslim and Jewish holy sites are located.

Trump’s justification for the move – one he was advised against by officials of the US administration – is expected to be that the Israeli legislature and several government offices are in Jerusalem. Officials said he will also order the US State Department to begin the process of moving the embassy to Jerusalem from Tel Aviv, a process that is likely to take at least three years, Reuters reported.

On Tuesday, Turkish President Recep Tayyip Erdogan warned the US against formally recognising Jerusalem as the Capital of Israel. He said Turkey would cut ties with Israel if Trump made the announcement.