President Trump plans to recognize Jerusalem as the capital of Israel and move the American Embassy there, upending nearly seven decades of American foreign policy and potentially destroying his efforts to broker peace between Israel and the Palestinians.
Mr. Trump’s decision, a high-risk foray into the thicket of the Middle East, was driven not by diplomatic calculations but by a campaign promise. He appealed to evangelicals and ardently pro-Israel American Jews in 2016 by vowing to move the embassy, and advisers said on Tuesday he was determined to make good on his word.
But the president, faced with a deadline of this past Monday to make that decision, still plans to sign a national security waiver to keep the embassy in Tel Aviv for an additional six months, even as he set in motion a plan to move it to Jerusalem. Officials said the process would take several years.
More significantly, Mr. Trump is to announce his formal recognition of Jerusalem as the Israeli capital in a formal speech at the White House on Wednesday, when he will become the first American president to take that step since the founding of Israel in 1948.
Mr. Trump spent Tuesday morning explaining the policy change in telephone calls with Prime Minister Benjamin Netanyahu of Israel; Mahmoud Abbas, the Palestinian Authority president; and to Arab leaders who warned him that it would disrupt the peace process, perhaps fatally, and could unleash a new wave of violence across the region.
“Moving the U.S. embassy is a dangerous step that provokes the feelings of Muslims around the world,” King Salman of Saudi Arabia told Mr. Trump in their call, according to Saudi state television.
Late on Tuesday, Palestinian national and Islamic groups issued a joint statement calling for three days of “popular anger” to protest Mr. Trump’s move, beginning on Wednesday throughout the Palestinian territories and in demonstrations at United States embassies and consulates around the world.
Fearing attacks, the American consulate in Jerusalem barred employees and family members from going to the Old City or the West Bank, while the State Department urged embassies around the world to tighten their security.
Jerusalem is one of the world’s most fiercely contested swaths of real estate, with both sides disputing each other’s claims. West Jerusalem is the seat of Israel’s government, but the Palestinians view East Jerusalem as the capital of a future Palestinian state, and most of the world considers it occupied territory. Jerusalem’s Old City has the third-holiest mosque in Islam and the holiest site in Judaism, making the city’s status a sensitive issue for Muslims and Jews worldwide alike.
Mr. Trump’s decision drew applause from some in Israel and the United States, even if Mr. Netanyahu and the Israeli government were studiously silent in advance of the president’s speech.
“The U.S. recognizing Jerusalem as Israel’s capital is a positive and important step, particularly amid Palestinian efforts to undermine the historic ties between the Jewish nation and the City of David,” said Amos Yadlin, executive director of Tel Aviv University’s Institute for National Security Studies.
Morton Klein, president of the Zionist Organization of America, said, “It is high time to move the embassy to Jerusalem.” He added, “Not moving it to Jerusalem for 22 years has not brought us closer to peace.”
White House officials said Mr. Trump remained committed to what he has called the “ultimate deal” between Israel and the Palestinians. The decision, they said, was “recognition of current and historic reality.” They said it could hasten, rather than impede, peace negotiations by removing a source of ambiguity from the American position.
Mr. Trump, officials said, would make clear that the United States is not taking a position on whether, or how, Jerusalem is divided between Israel and the Palestinians. He will also not take a position on a disputed area of the Old City, known as the Temple Mount to Jews and the Haram al-Sharif to Muslims, which has been a flash point for tensions.
But even with those caveats, Mr. Trump’s decision seems likely to disrupt, if not dissolve, the peace effort. Administration officials said they expected the Palestinians to walk away from the process, at least for now. The White House is girding itself for an eruption of violence, coordinating plans with several agencies to protect American citizens abroad.
“You can finesse this all you want, but Jerusalem doesn’t allow for any finesse,” said Martin S. Indyk, a former American ambassador to Israel. “They can try to limit the damage all they want, but they won’t be able to, because Jerusalem is such a hot-button issue.”
To some extent, Mr. Trump’s willingness to take such a risk underscores how little progress his peace negotiators — led by his son-in-law, Jared Kushner — have made. Six months ago, when the president last had to decide whether to sign a waiver to keep the embassy in Tel Aviv, Mr. Kushner prevailed on Mr. Trump to do so, in the interest of the peace process.
Since then, however, the administration’s efforts have shown little evidence of narrowing the differences between Israelis and Palestinians. Mr. Kushner and Jason D. Greenblatt, the president’s special envoy, supported Mr. Trump’s decision, officials said.
Mr. Trump’s pledge was extremely popular with evangelicals and pro-Israel backers, including the casino magnate Sheldon Adelson, who donated $25 million to a political action committee supporting Mr. Trump during the presidential campaign. Mr. Adelson expressed anger when Mr. Trump signed the waiver in June to keep the embassy in Tel Aviv.
The White House, which has done little to lay the groundwork for the move, on Tuesday contacted pro-Israel leaders from the Jewish and Christian communities to invite them to a conference call set for Wednesday afternoon, according to an invitee who spoke about it on condition of anonymity because he did not want to jeopardize his relationship with Mr. Trump’s team.
Mr. Klein was among several supporters who questioned why the embassy move would take several years. Former diplomats have said that the United States could relocate the embassy simply by hanging a new sign outside the American consulate in Jerusalem.
White House officials, however, said the administration’s lawyers concluded that would not be in compliance with a 1995 law, under which Congress instructed the president to move the embassy and required him to sign a waiver every six months to delay it. Legally, the officials said, the United States would have to move embassy staff into the building as well.
Reaction to Mr. Trump’s move in the Arab world was swift and negative, even from normally friendly leaders.
King Abdullah II of Jordan strongly cautioned against the move, “stressing that Jerusalem is the key to achieving peace and stability in the region and the world,” according to a statement from the royal palace in Amman. The Hashemite Kingdom of Jordan is the custodian of Al Aqsa Mosque in Jerusalem.
“King Abdullah stressed that the adoption of this resolution will have serious implications for security and stability in the Middle East, and will undermine the efforts of the American administration to resume the peace process and fuel the feelings of Muslims and Christians,” the statement said.
Few details of the conversation between Mr. Trump and Mr. Abbas were released, but a spokesman for the Palestine Liberation Organization said the call had given shape to the worst fears of Palestinians.
“It’s very serious,” said the P.L.O. spokesman, Xavier Abu Eid. “Things look very bad.” The Palestinian news agency, WAFA, quoted Mr. Abbas’s spokesman, Nabil Abu Rudeineh, as saying that Mr. Abbas will continue his contacts with world leaders to prevent such “unacceptable action.”
King Abdullah also spoke with Mr. Abbas, assuring him of Jordan’s support for the Palestinians “in preserving their historic rights in Jerusalem and the need to work together to confront the consequences of this decision,” it said.
Mr. Trump, officials said, assured Mr. Abbas that the administration would protect Palestinian interests in any peace negotiation with Israel. He also invited the Palestinian leader to visit him in Washington for further consultations. Mr. Abbas said he could not come for a while.