Seventeen months after the United States and Iran began negotiating a possible return to the 2015 Iran nuclear deal abandoned by President Donald J. Trump, the European Union has presented a “final” proposal for the two sides to consider before the talks collapse for good, Western officials said.
The negotiations have carried on through many pauses, crises and threatened conclusions, and it is far from certain that the latest proposal represents a final chapter. But U.S. and E.U. officials say their patience has worn paper thin, as Iran steadily expands its nuclear program.
“What can be negotiated has been negotiated, and it’s now in a final text,” the E.U. foreign policy chief, Josep Borrell Fontelles, said Monday on Twitter.
U.S. officials have long warned that time is running out to reach an agreement. A State Department spokesman, speaking on the condition of anonymity to discuss sensitive negotiations, said the United States was “ready to quickly conclude a deal” and that the E.U. proposal was “the only possible basis” for it.
U.S. officials are skeptical that Iran is prepared to roll back its program in exchange for relief from sanctions that have weakened its economy. But some analysts say the sides have inched closer than had been expected.
In a notable shift, Iran has retreated from two key demands. One is an insistence that the United States remove Iran’s Islamic Revolutionary Guards Corps from its official list of foreign terrorist organizations, according to people briefed on the negotiations and two Iranians familiar with the talks.
The other is an insistence that the Biden administration provide guarantees that a future president will not withdraw from the deal even if Iran upholds its commitments, as Mr. Trump did in 2018. The Iranians have come to accept that such a promise is not possible, according to the two Iranians.
“We are closer than we have been since the deal was all but done last May, before the talks suspended for the Iranian elections,” said Joseph Cirincione, a nuclear policy expert who consulted closely with the Obama administration during talks to strike the original nuclear deal. “Bottom line: It could happen.”
Such a breakthrough would provide Mr. Biden with a foreign policy achievement as he heads into midterm elections in the fall, though some European officials say the American president may be wary of political criticism over renewing an Obama-era agreement that Republicans almost uniformly denounce and that even some key Democrats opposed in its original form.
Another factor is a fresh Iranian demand that the International Atomic Energy Agency, the U.N. nuclear watchdog, drop a three-year investigation into unexplained man-made uranium at various Iranian research sites, including some that Tehran refuses to let I.A.E.A. inspectors visit. Iran vehemently denied that it had military intentions for enriched uranium.
“This is their style: moving toward an agreement but at the moment of agreement saying, ‘There’s just one more thing,’” Mr. Cirincione said.
The agency identified traces of uranium particles based on information uncovered in 2018, when Israeli agents stole thousands of documents and CDs about Iran’s nuclear program from a Tehran warehouse.
The stolen documents indicated that Iran had a military nuclear program until at least 2003, when the United States believes it ended. Israel remains unconvinced that it was shut down.
Iran has made dropping the investigation key to its approval of the nuclear deal, even though the I.A.E.A. is not a signatory to it and was not engaged in the negotiations.
The agency’s secretary general, Rafael M. Grossi, has also said that it would be difficult for the agency to restore with full confidence an assessment of where Iran is on enrichment because the country has banned the agency from replacing full memory cards and cameras for months, as part of its own effort to pressure the negotiators.
“Just like in 2015, it is very hard to delink Iran’s past from its future,” said Ellie Geranmayeh of the European Council on Foreign Relations, who tracks the negotiations.
“Iran wants to close the I.A.E.A. investigations into its past as part of reviving the J.C.P.O.A.,” she added, using the abbreviation for the original agreement. “The West is not willing to drop the investigation.”
Ali Vaez, the Iran director for the International Crisis Group, said that “what Iran gets wrong is that it can’t wish away the U.N. inspections doing their job.”
“What it needs to do is to come clean once and for all,” Mr. Vaez said. “The parties managed to resolve several issues, which is a positive development. But the fact that there is a single disagreement left doesn’t guarantee success.”
Even if finally signed, the new deal would take months to enact. Critics noted that even if Iran agreed to the enrichment limits in the original deal, the country has enough knowledge to build a nuclear weapon if it chose to do so, making it a “threshold state.”
Iran also does not accept that the current 35-page proposed agreement is a closing bid. Nour News, a news media outlet for the Supreme National Security Council, said on Tuesday that “naturally the Islamic Republic of Iran does not accept the current text as the final text.”
After Mr. Biden refused in the spring to lift the U.S. designation on the guard corps, Iran installed new advanced centrifuges in places deep underground and enriched uranium to 60 percent, which is close to weapons grade and not needed for any civilian use.
In Iran, many analysts doubt that a deal is within reach. Iran’s conservative government faces internal divisions, and hard-line factions distrust the West. Making key concessions also risks political backlash. Some conservative lawmakers have said any agreement that leaves the guards corps designated as a terrorist group is unacceptable.
But if Iran’s supreme leader, Ayatollah Ali Khamenei, declines the current Western offer, Iran would probably not abandon the talks. Iran sees itself as holding leverage over a West eager for a deal that would bring more Iranian oil into a global economy strained by high energy prices, analysts said. But Ayatollah Khamenei is also eager to remove constricting sanctions.
Mr. Vaez said that if this attempt at an agreement fails, the West will have to start pondering more limited alternatives.
“They are then likely to explore alternative options, like an interim deal, against the backdrop of an intensified race of sanctions versus centrifuges,” Mr. Vaez said.