WASHINGTON -- U.S. President Donald Trump has announced that "it is time to officially recognize" Jerusalem as the capital of Israel.

Trump in his December 6 speech also said that he has ordered the State Department to begin preparations to move the U.S. Embassy from Tel Aviv to Jerusalem, a move experts say could take three to four years.

Trump’s endorsement of Israel’s claim to all of Jerusalem as its capital reverses a decadeslong U.S. policy that the city’s status must be decided in negotiations with Palestinians, who want East Jerusalem to be the capital of their future state.

In his speech, Trump said that he still intends “to do everything in my power to help force” a peace agreement acceptable to both Israelis and Palestinians.

Israeli Prime Minister Benjamin Netanyahu hailed Trump's declaration as “historic” and urged other countries to follow the United States by moving their embassies to Jerusalem.

Palestinians and Arab leaders, as well as key U.S. allies, have warned Trump that the move risks triggering violence across the entire Middle East and complicating the peace process.

Most nations do not recognize Israeli sovereignty over the entire city, which includes sites considered holy by Muslims, Jews, and Christians.

U.S. officials have insisted that Trump’s decision to fulfill a key campaign promise was not meant to prejudice the outcome of eventual negotiations on the final status of Jerusalem.

They said Trump’s announcement reflects the “historic reality” that Jerusalem is the center of the Jewish faith and the “modern reality” that it is the seat of Israel’s government, although most nations maintain their embassies in Tel Aviv.