As they await his arrival Monday in Jerusalem, Israeli officials are trying to attune themselves to Trump's free-wheeling approach to diplomacy and a new cast of unlikely, untested advisors, including Trump's son-in-law and two of Trump's long-time personal attorneys.
They worry in part because since taking office, Trump has hesitated on his campaign pledge to move the U.S. Embassy from Tel Aviv to Jerusalem.
Trump's visit comes a week before he must sign the same national security waiver that his predecessors have signed every six months since 1995 to keep the embassy in Tel Aviv.
Newly-arrived U.S. Ambassador David M. Friedman, Trump's former bankruptcy lawyer, scrambled this week to reassure Prime Minister Benjamin Netanyahu's government that Trump remains as firmly committed to Israel as ever.
But Friedman told the Israelis that Trump isn't expected to announce a decision about the move during the trip.
The delay has frustrated right-wing politicians in Israel who fear Trump may back down on other promises.
In February, Trump issued mild criticism of Israel's continued building of settlements in the West Bank, saying that new construction doesn't help the peace process. The rebuke surprised Netanyahu's government, which had just announced plans to build thousands of new homes in the disputed territory.
Earlier this month, Israeli officials needed reassurance as well when Trump welcomed
Trump is expected to visit Abbas in Bethlehem on Tuesday, even though some in the Israeli government had hoped Trump would snub the Palestinian leader during the trip.
"The uncertainty is very high," said a former Israeli diplomat who was stationed in the United States.
It also didn't help when Trump last week shared classified material about Islamic State militants with Russian diplomats. The information reportedly originated with Israeli intelligence and was shared with the U.S. on the condition that it not be passed along to others, according to media reports.
Israeli officials know little of the intentions of Trump's advisors. Even Trump's son-in-law, Jared Kushner, who has been managing the White House's relationship with Israel over the past few months, has generated some skepticism among hard-liners, despite the fact the he is Jewish, he has known Netanyahu for many years and his family has helped fund Jewish settlements in the West Bank.
Kushner also manages the White House relationship with Saudi Arabia and the Arab world.
In addition to sending Friedman to Tel Aviv, Trump tapped his former real estate attorney Jason Greenblatt to help manage the peace process with the Palestinians. He regularly hears advice on Israel from friends including New England Patriots owner Robert Kraft and American casino magnate
Israeli officials are having to adjust to Trump and these new advisors after years spent dealing with a familiar set of Washington diplomats and Middle East experts, Michael Oren, the Israeli deputy minister for diplomacy and a former ambassador to the U.S., said.
Oren brushed aside the notion there have been hiccups and said the Israelis are confident in Trump's ardent support.
"This is an administration which is unequivocally committed to Israel's security, sees it as an indispensable ally and is deeply opposed to doing anything that would impair our security," Oren said.
But they will closely watch the signals Trump sends during his two-day visit, which will include a tour of the Holocaust memorial at Yad Vashem, a speech at the Israel Museum, and the first visit by a sitting U.S. president to the Western Wall, one of Judaism's holiest sites.
During official preparations for Trump's visit to the wall in the Old City, a U.S. diplomat inflamed Israeli officials by reportedly saying the revered structure is in disputed territory and doesn't belong to Israel. Although Israel annexed the Old City along with all of East Jerusalem after the 1967 Six-Day War, Palestinians and most of the international community consider it part of the occupied West Bank.
Officials within Netanyahu's right-wing government are deeply suspicious of the U.S. foreign service and other parts of American bureaucracy, and are concerned that Trump will be eventually swayed by entrenched American policy towards Israel.
In private meetings during Trump's visit, Israeli officials are looking for assurances that Trump will work with them to counter Iran's moves in the region. The U.S. Treasury Department's decision Thursday to put new sanctions on seven targets involved in Iran's ballistic missile program was aimed at soothing concerns in Israel as well as signaling to Saudi Arabia that the U.S. would take a hard stance against Iranian intervention in Yemen.
Both Israel and Saudi Arabia felt sidelined by the Obama administration and complained that former Secretary of State John F. Kerry, in pursuit of the Iran nuclear deal, gave Iran a long leash to project power in conflicts in Syria and Yemen. White House officials believe those complaints have created a unique moment to bring Arab and Israeli interests together in countering Islamic extremists as well as building regional support for a peace deal between Israelis and Palestinians, though such efforts have failed in the past.
Trump's initial steps could include convincing Gulf states to make some partial moves toward regional support for a peace deal or bringing Netanyahu and Abbas together for the first time in seven years, said David Makovsky, a former member of the U.S. negotiating team under Kerry.
Trump shouldn't try for a "home run," or a full-fledged agreement between the Israelis and Palestinians, Makovsky said. "When you try to hit the ball out of the park, the odds of striking out are greater," Makovsky said, pointing to past failed attempts. "But this president might feel he only does home runs; he doesn't want a single."
Trump is singularly fixated on delivering a Middle East peace deal, White House officials said, even if that means jettisoning the long-standing U.S. stance that any resolution should be based on a two-state solution. Others in his administration, including Nikki Haley, the ambassador to the United Nations, have said the U.S. remains committed to a two-state solution.
Trump's willingness to consider other endgames to the Israeli-Palestinian stalemate has sent State Department diplomats to the history books, dusting off decades-old alternatives to a two-state solution, such as Jordanian rule, confederacy and economic autonomy.
As Trump prepares to land in Israel, his unconventional approach has added to a mood of confusion and caution, said retired Israeli Admiral Ami Ayalon.
Those who didn't believe in a two-state solution see Trump "as the messiah who would save Israel from the traditional, old concept of two states," Ayalon, the former director of Israeli domestic security agency Shin Bet and cofounder of the Blue White Future, a political advocacy group, said in an interview.
"He is a different president. He doesn't owe anything to the [American] Jewish community — most didn't vote for him— and he doesn't depend on Jewish money. That makes him much more flexible," Ayalon said. "Bottom line: No one quite knows what to expect."
Staff writers Noah Bierman and Tracy Wilkinson in Washington and special correspondent Joshua Mitnick in Jerusalem contributed to this report.