“It’s really a question of what are the lines, the borders, to be drawn around the state of Israel and the ultimate state of Palestine,” Mr. Walker said. “Nothing in what the president has said precludes the negotiation of a settlement of this issue.”
That was not the prevailing view. More typical was the perspective of Daniel C. Kurtzer, who was the ambassador from 2001 to 2005, under President George W. Bush.
“There are many downsides, both diplomatically and in terms of the Middle East peace process, and no upside,” Mr. Kurtzer said. “We are isolated internationally once again — except for the Israeli government, which supports this — and we are taking ourselves out of the role the president says he wants to play as a peace broker.”
What of the argument that the peace process, with the goal of a two-state political solution, was dormant, and needed to be shaken up?
“The fact that the process is moribund calls for a much more dramatic role,” he said. “It doesn’t call for the U.S. to lean over and adopt the position of one party and offer nothing to the other party.”
Richard H. Jones, who was ambassador from 2005 to 2009, also under Mr. Bush, warned that groups like Hamas and the Islamic State would exploit the issue to incite violence, and predicted that the Palestinian Authority would step up international efforts to boycott and condemn Israel.
“This is a risky move, which no doubt will cost lives in Israel and the region, particularly as Israeli settlers use it to justify accelerating their activity further,” he said in an email.
Several of the ambassadors were open to recognizing West Jerusalem as Israel’s capital. But they said that should happen as part of a broader strategy that would also require the Israelis to halt or slow settlement construction and that would recognize East Jerusalem as the capital of a future Palestinian state.
Martin S. Indyk, who served as ambassador twice, both times during Bill Clinton’s presidency, proposed just such a deal in an Op-Ed essay in The New York Times this year, weeks before Mr. Trump was sworn in.
“Not surprisingly, President Trump didn’t follow my advice to couple his move on Jerusalem with a diplomatic initiative,” Mr. Indyk said on Thursday. “Instead, he tried to limit the damage by avoiding any geographic definition of the capital that he is officially recognizing. Unfortunately, that nuance will be lost on all sides.”
William Andreas Brown, who was the ambassador from 1988 to 1992, and returned to the United States Embassy in Israel as chief of mission early in the Clinton administration, recalled that he once wrote a memo to the first President George Bush urging that the embassy be moved to Jerusalem.
“My motivation was to incentivize Israel’s participation in the Madrid peace talks,” he said, referring to negotiations in 1991 that helped give momentum to what later became the Oslo process. He recalled that there was significant resistance to the proposal in the Bush administration, and that the idea was dropped.
“If he was going to make this announcement, it ought to be very, very carefully crafted so as to minimize a blowup,” he said, making clear he did not think Mr. Trump had succeeded.
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William Caldwell Harrop, who was the ambassador from 1992 to 1993, called Mr. Trump’s decision “slightly reckless” and even “kind of a masochistic move” that might “undermine his own, repeatedly discussed, ‘great deal’ of bringing peace to the Israelis and Palestinians.”
Having decided to make his announcement, Mr. Trump could have been explicit that he would place the embassy in West Jerusalem, Mr. Harrop said.
“One has to be pessimistic,” he said after listening to Mr. Trump’s speech. “We’ll get, before long, more efforts by Palestinians to build up international recognition of the state of Palestine. Some form of intifada is very likely, and there will be more bloodshed.”
Edward P. Djerejian, who was the ambassador from 1993 to 1994, in the optimistic aftermath of the Oslo peace accords, also found Mr. Trump’s effort to thread the needle unsatisfying.
Mr. Trump portrayed his decision more as a recognition of on-the-ground reality than as a sharp change in policy, insisting that “the specific boundaries” of Israeli sovereignty in Jerusalem had yet to be settled.
But Mr. Djerejian, who was a White House spokesman during the Reagan presidency, said there was “an inherent contradiction” in recognizing Jerusalem without saying what, exactly, comprises Jerusalem. “The timing and substance of this new position serves to confuse rather than clarify,” he said.
James B. Cunningham, who was ambassador under President George W. Bush and President Barack Obama, called Mr. Trump’s decision “a pretty serious mistake,” and said that moving the embassy would have made sense only as “part of a strategy, not simply to demonstrate that you’re trying to do something different.”
He added, “It doesn’t make Israel safer, the United States safer, or the region more stable.”
The most recent former ambassador, Daniel B. Shapiro, who served under Mr. Obama, was sympathetic to Mr. Trump’s goal, if not the execution.
“Jerusalem is Israel’s capital, and it’s appropriate that we recognize it as such,” he said in a phone interview. “In that sense, the president’s recognition of reality is fine.”
He continued: “The missed opportunity here, though, is the failure to frame this decision in the context of achieving our broader strategic objective, which is a two-state solution. That would have required better prior consultation with Arab states. That would have required more clarity for what the Palestinians could expect as part of their aspirations for Jerusalem.”
He said the decision might undermine the peace process that Mr. Trump’s son-in-law, Jared Kushner, and special representative, Jason Greenblatt, have been working on.
Most of the former ambassadors were reluctant to ascribe motivations to Mr. Trump, though several said the move would bolster his support among hard-line supporters of Israel in the United States and among some evangelical Christians.
However, Thomas R. Pickering, who was ambassador to Israel during the Reagan administration, called it “a serious foreign policy mistake” and an attempt either at “ego satisfaction” or an effort to divert attention from a special counsel’s investigation into the Trump campaign’s ties with Russia.
In an interview, Mr. Pickering compared Mr. Trump’s move to the film “Wag the Dog,” in which a president fabricates a war to distract attention from a sex scandal.