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Germany, France and the United Kingdom have signaled that they will trigger the reimposition of United Nations sanctions on Iran in the coming days, three European officials told CNN Wednesday. The so-called “snapback” mechanism that is part of the 2015 Iran nuclear deal could be initiated as soon as Thursday, one of the officials said.

The process takes 30 days to complete, leaving European leaders with a small window of time in which to pursue diplomacy. If the sanctions snapback is set in motion, they hope Tehran will use that time to return to the negotiating table in earnest, open its facilities to international inspectors, and take steps to come back into compliance with its nuclear obligations.

But Iran has also signaled in recent days that it will take “unhesitant” revenge if the sanctions snapback is carried out. Renewed sanctions would come on top of crushing economic pressure that has increased in recent years and, like the decision to restart nuclear enrichment, is likely to further destabilize a Middle East already reeling from the recent conflict.

Snapback mechanism expires in October

As part of the 2015 Joint Comprehensive Plan of Action (JCPOA) nuclear deal, the snapback provision would allow members to restore UN sanctions on Iran if it is found in violation of the deal. The provision’s ability to trigger the sanctions snapback expires in October.

Iran has significantly expanded its nuclear program since former President Donald Trump pulled out of the deal in 2018, with facilities operating well beyond the enrichment limits put in place by the JCPOA. The Trump administration also unilaterally re-imposed sanctions that were removed as part of the deal.

Iran says its program is for peaceful purposes, but its growing capabilities have drawn increasing alarm from inspectors and outside analysts who say its facilities are approaching the threshold of weapons-grade capability.

“Going back to the original JCPOA would be almost impossible,” Rafael Grossi, the head of the International Atomic Energy Agency (IAEA), said in a press conference Wednesday.

The current U.S. Secretary of State Marco Rubio, who met with his European counterparts this week to coordinate their next steps, told reporters the snapback is “a very powerful piece of leverage on the Iranian regime.”

Inspectors return despite warning by Iran’s parliament

While Iran’s parliament passed legislation earlier this month instructing the government to end all cooperation with international inspectors, they have since quietly returned to several facilities, Grossi confirmed Wednesday.

“We have inspectors on the ground in Iran today, and we are in the country, for example, at the Bushehr nuclear power plant,” he told reporters in Washington.

Grossi said inspectors were carrying out checks in that facility and elsewhere to “monitor the change of fuel that is underway in that plant,” the head of the IAEA said. “Today we are inspecting Bushehr,” he told reporters in Washington. “We are continuing the conversation so that we can go to all places, including the facilities that have been attacked.”

IAEA’s safeguards come from the Nuclear Non-Proliferation Treaty (NPT), which Iran is a signatory to, and they would continue to hold until Tehran leaves the NPT, which is reportedly one of their options should the UN sanctions snapback be carried out.

Iranian Foreign Minister Abbas Araghchi acknowledged the inspectors were monitoring fuel replacement at the Bushehr facility on Wednesday. The decision to allow them in was made by Iran’s Supreme National Security Council, he said. “It is not an agreement to ‘new cooperation’ or anything like that,” he said.

Fallout from recent conflict

Inspection access was a major point of contention between Tehran and the IAEA, and the agency withdrew its inspectors in July following an incident at a facility that Tehran said had exposed one of its workers to radiation.

In an interview with CNN in July, Grossi said the inspectors left Iran due to the wartime conditions, which made monitoring and inspection impossible. Satellite imagery at the time showed that entrances at Iran’s Isfahan Nuclear Technology Research Center had been destroyed.

Iran has since accused the IAEA of effectively giving Israel the pretext it needed to strike the country’s nuclear facilities last month, after the agency released a report on Iran’s non-compliance with the safeguard rules.

Divisions in Iran over allowing inspections

The decision by Iran’s government to allow the IAEA back into some of the facilities has sparked pushback in parliament. Parliamentary member Kamran Ghazanfari wrote in a post on X that Speaker Mohammad Bagher Ghalibaf’s remarks on the limited inspections the agency had been allowed were an “explicit violation” of laws suspending all cooperation with the agency.

Iran’s parliament passed the legislation in July following the conflict that began after Israel targeted Iran’s nuclear facilities on June 13, starting a 12-day conflict in which Iranian retaliatory strikes hit Israeli cities. U.S. forces joined the fight in the last days, striking three sites in Iran in an operation that Israel did not acknowledge until after the fighting was over.

European negotiators held a day of talks in Geneva on Tuesday with Iranian representatives in a last-ditch effort to avoid the sanctions snapback, one of the European officials said. Sources familiar with the discussions said little progress was made during the talks.

Rubio’s European counterparts had met with U.S. officials in Geneva in the days leading up to the Israel-Iran fighting, hoping to build a diplomatic path forward for a new nuclear deal. U.S. envoy Steve Witkoff was engaged in talks until the conflict began and were carried out in the days that followed, which all collapsed when the fighting began.

Grossi said he was cautiously optimistic, however, that the next 30 days could see some de-escalation in the nuclear arena. “Don’t forget that there is still time, even if there is the triggering thing, there is a month, and many things could happen,” he said Wednesday.

The European trio has until October to carry out the sanctions snapback as the provision that allows them to do so will expire. The coming weeks will show whether diplomacy has a role to play in the next chapter of the Iran nuclear saga, or if the United States and Europe will escalate the pressure and Iran the confrontation.