US has resumed indirect talks with Iran in effort to constrain nuclear program

The United States has quietly resumed indirect talks with Iran in an effort to constrain Tehran's nuclear program, multiple sources told CNN.

The talks resumed late last year, months after an effort to revive the Iran nuclear deal collapsed. The Trump administration withdrew from the landmark agreement in 2018 and Iran has increasingly grown its nuclear program in violation of the deal, formally known as the Joint Comprehensive Plan of Action (JCPOA).

Although sources say there have been some indications of progress, one source said "we're just not there yet" on an agreement, and both the US and Iran have denied that an interim deal has been reached.

Stakes are high for the renewed efforts, which come ahead of the 2024 US presidential election and will face scrutiny from lawmakers and a key US ally in the Middle East: Israel.

The US is also engaged in trying to secure the release of multiple Americans who have been detained in Iran - something the administration has called a top priority. There are three Americans who have been designated as wrongfully detained who are imprisoned in Iran: Siamak Namazi, Emad Sharghi, and Morad Tahbaz. An American resident, Shahab Dalili, is also detained.

Biden administration officials have for months said that Iran's breakout time - how long it would need to produce enough weapons-grade material for one nuclear bomb - had dwindled to a matter of weeks, with one Defense Department official saying in February that it could be as short as 12 days. The breakout time does not mean that Iran could produce an actual bomb in that period.

For months following the failure of the JCPOA revival attempt and amid nationwide protests in Iran, the Biden administration said publicly that the nuclear deal was "not on the agenda," but said that they were committed to using diplomacy to prevent Iran from acquiring a nuclear weapon.

However, talks quietly resumed late last year, with countries including Oman serving as intermediaries. A top administration official, Brett McGurk, has traveled multiple times to the Gulf nation for the indirect discussions with Iranian government representatives.

And in what could be seen as a confidence building measure, the US approved a waiver allowing the transfer of $2.7 billion from Iraq to Iranian banks, in a move State Department spokesperson Matthew Miller called "consistent with transactions that have taken place over - going back a number of years."

"Number one, Iran can only access its funds held in accounts for Iraq for humanitarian and other non-sanctionable transactions," he said Tuesday. "Number two, that these are actions that have taken place for several years, dating back to the previous administration, where the United States has approved similar transactions on an ongoing basis, consistent with US law and in full coordination with the Government of Iraq."

Iran's foreign ministry spokesperson said Monday that Tehran exchanged messages with the United States through Oman "a few weeks ago."

"The basis of the negotiations to lift sanctions is the JCPOA. We do not have a new framework. We do not endorse any negotiations for an interim agreement or new arrangements to replace the JCPOA," Nasser Kanaani said in a briefing.

Israeli Prime Minister Benjamin Netanyahu suggested this week that his government would remain opposed to a deal with Tehran, reportedly saying, "Our position is clear: Israel will not be bound by any deal with Iran and will continue to defend itself."

On Thursday, US Secretary of Defense Lloyd Austin met with his Israeli counterpart in Brussels, where "both leaders agreed to continue working together to address the wide range of threats posed by Iran, including its nuclear program, destabilizing regional activities, and proliferation of uncrewed aerial systems and other lethal assistance throughout the Middle East and to Russia," according to a Pentagon readout.

Earlier this week, Iranian negotiator Ali Bagheri Kani met with officials from the so-called E-3 countries - France, Germany, and the United Kingdom - in Abu Dhabi, UK Foreign Office political director Christian Turner said on Twitter.

If an agreement on the nuclear issues was reached, it is unlikely it would restore the limits of the JCPOA, but would rather be an effort to put a box around Iran's growing nuclear program.

"They've moved on to what you would call Plan C, which is try to constrain Iran and try to limit worst case outcomes, but without trying to reach an actual agreement for the next year plus given the political constraints that the administration faces and not wanting to draw attention or resources away from China and Russia," said Henry Rome, a senior fellow at the Washington Institute.

A US official told CNN that the administration's diplomatic engagements were focused on "constraining its destabilizing behavior and ensuring it does not acquire a nuclear weapon." They said they want to see Tehran curb its nuclear program, stop supporting proxy groups carrying out attacks in the region, and stop supporting Russia in its war in Ukraine.

"We continue to use our diplomatic engagements to pursue all of these goals, in full coordination with our partners and allies," the official said.

"We believe diplomacy is the best path forward, as we have said since the outset of this Administration. But, as always, we have other options available to us if Iran chooses not to act," they said, adding that their "diplomacy is matched and backed by deterrence."

"Our actions earlier this year, for example, sent a clear message to Iran, which have resulted in a significant reduction of attacks against US personnel," the official said.

On the issue of the detainees, Oman's foreign minister told al-Monitor that the two sides are "close."

"This is probably a question of technicalities," he told the publication.

In the past, one aspect of a prospective deal for the detainees has involved the unfreezing of billions of dollars of frozen Iranian assets from South Korea.

CNN's Mostafa Salem contributed reporting