JERUSALEM — When the United States last tried to negotiate a nuclear deal with Iran, the reaction from the Israeli government was blunt and fierce. In the years preceding Iran’s 2015 agreement with Washington and several other leading powers, Prime Minister Benjamin Netanyahu of Israel repeatedly called their negotiations a “historic mistake,” even making a speech to Congress in 2015 decrying the Obama administration’s openness to a deal.
But on Friday, the formal announcement that the Biden Administration was seeking a return to nuclear negotiations with Iran, following the collapse of the 2015 agreement under President Donald Trump, was initially met with a muted response — not just in Jerusalem, but also in the Gulf States of Saudi Arabia and the United Arab Emirates, which also oppose too generous a rapprochement with Iran.
On Friday afternoon, Mr. Netanyahu’s office issued a brief statement, avoiding direct comment on the negotiations, but noting that Israel was in contact with the United States.
“Israel remains committed to preventing Iran from getting nuclear weapons, and its position on the nuclear agreement has not changed,” the statement said. “Israel believes that going back to the old agreement will pave Iran’s path to a nuclear arsenal.”
Western diplomats and former Israeli officials said that the Israelis were still digesting the news and working out how to respond, but that they accepted the need to engage constructively with Washington instead of dismissing the negotiations out of hand.
“The question is,” said Tzachi Hanegbi, Israel’s minister for community affairs, in an interview with The New York Times on Friday, “what is the policy of the new administration vis-à-vis the outcome of the negotiations?”
The Israeli government was not intrinsically opposed to negotiations, Mr. Hanegbi said. But the talks had to result in a better deal than the one agreed to in 2015, which Israel and the Gulf countries condemned because its restrictions on Iranian nuclear activities would expire within a decade and a half, and it did little to curb Iranian military activity across the Middle East.
“We would like the negotiations to emphasize what the world would like to see: an agreement for a longer time — for at least 50 years, if not more,” Mr. Hanegbi said. Israel cannot accept “an agreement that will expire in four to five years,” he added. “It has to be an agreement that will be valid for generations. Anything else will not achieve the goal of preventing a nuclear Iran.”
Saudi and Emirati officials were silent on Friday. Watching the Biden administration’s outreach to Tehran with resignation, the two Gulf States — which were outraged at being excluded from the last round of negotiations — can only hope that the United States will keep its promises to make sure Gulf interests are represented in the talks, analysts said.
“We just have to trust the new administration; we don’t have any option,” said Abdulkhaleq Abdulla, an Emirati political scientist. “They really are determined to reach out to Iran, so there’s no way that anybody could stop them.”
But he acknowledged there could be something to gain, saying, “If the end result is less confrontation with Iran, a less aggressive Iran, a less expansionist Iran, it’s a dream of a sort.”
The Israeli government has yet to enunciate a clear response to the American policy shift, said Amos Yadlin, a former head of Israeli military intelligence. But at least initially, he said, it will take a much less combative approach to the Biden administration’s policymaking than it did with President Barack Obama’s.
“I think they will be very careful,” Mr. Yadlin said of the Israeli government. “The Americans haven’t returned to the agreement yet, and they will try to create a dialogue that will help the Americans to achieve a longer and stronger agreement.”
He added: “Practically, they will not confront the Biden administration directly. They will wait a little bit to see whether the Iranians are reacting and how the negotiations develop.”
In Europe, where leaders have long hoped America would return to the table with Iran, there was a more positive response. “The U.S.A. is giving diplomacy a chance,” Germany’s foreign minister, Heiko Maas, wrote on Twitter. “We expressly welcome and support this!”
Mr. Maas also warned Iran against taking aggressive measures precisely at a time when diplomatic breakthroughs seemed possible. “Now the Iranian leaders must also show that they are serious,” he said.
In Russia — an ally of Iran and a signatory to the nuclear deal — the Biden administration’s move meant that the Kremlin, for once, had something positive to say in Washington’s direction. In particular, it praised how the White House had also backed away from a Trump-era effort to restore United Nations sanctions on Iran.
“Halting the call for sanctions is a good thing, on its own,” said Dmitri S. Peskov, President Vladimir V. Putin’s spokesman. “This is an event that one can probably mark with a plus sign.”
In the Gulf region, which views Iranian expansionism as a major threat, the mood was more muted, with undercurrents of pessimism.
Ali Shihabi, a Saudi political commentator who is viewed as being close to the government, said Saudi Arabia had been signaling to the Biden administration for months that it supported re-engaging with Iran, but only if the goal was a deal more far-reaching than the 2015 agreement, known formally as the Joint Comprehensive Plan of Action.
“Now the question will be, is this just rhetoric and will the Biden people just produce effectively an identical recreation of the J.C.P.O.A., with all its flaws?” Mr. Shihabi said. “Or will it lead to a better agreement and some additional constraints on Iran’s regional behavior? The Biden people are making all the right noises, but the proof is in the pudding.”
Saudi Arabia has taken care to emphasize the positive in its relations with the Biden administration so far, wanting to show that it remains a constructive partner when it comes to Iran or other regional issues, said Eman Alhussein, a Saudi analyst at the Arab Gulf States Institute in Washington.
“They want to be seen as being part of the solution to these problems,” Ms. Alhussein said, adding that Saudi Arabia may be keen to do so because of the “atmosphere of apprehension” about the kingdom’s uncertain relationship with United States.
Biden officials have said they want to recalibrate the partnership in what would be an inevitably cool turn after four years of strong backing from the Trump administration.
Patrick Kingsley reported from Jerusalem, and Vivian Yee from Cairo. Reporting was contributed by Irit Pazner Garshowitz in Jerusalem, Steven Erlanger in Brussels, Roger Cohen in Paris, Melissa Eddy in Berlin and Anton Troianovski in Moscow.