Germany, France and the UK are about to activate a mechanism to reimpose United Nations sanctions on Iran, three European officials told CNN Wednesday. The so-called “snapback” clause from the 2015 Iran nuclear deal could be initiated as soon as Thursday.

The process to retrigger sanctions would take 30 days to take effect, which leaves a short period for diplomacy. European leaders are hoping that Tehran will take those three weeks to restart serious negotiations, reallow access to its facilities to international inspectors and take other steps to return to compliance with its nuclear commitments.

But Iran has said it would retaliate strongly if sanctions are reimposed, which increases the potential for further instability in a region already rocked by the fighting that began in June.

Snapback mechanism is due to expire soon

As part of the 2015 Joint Comprehensive Plan of Action (JCPOA), the snapback mechanism was designed to let members of the agreement reimpose United Nations sanctions on Iran in the event it did not adhere to the agreement. The ability to trigger the provision will expire in October.

Iran has continued to expand its nuclear program well beyond the parameters of the JCPOA since the United States pulled out of the deal under then-President Donald Trump. Tehran says its program is peaceful, but inspectors and analysts say it is getting ever closer to weapons-grade capability.

“It’s very simple: going back to the original JCPOA is almost impossible,” International Atomic Energy Agency (IAEA) Director Rafael Grossi said Wednesday.

US Secretary of State Marco Rubio said Wednesday that he had been in touch with European counterparts about sanctions this week and that the snapback is “a very powerful piece of leverage on the Iranian regime.”

Inspectors have returned to Iran

Inspectors have been back in Iran recently despite Iran’s parliament passing a bill in July to suspend cooperation with international inspectors.

Grossi said Wednesday that inspectors were in Bushehr, Iran’s nuclear power plant, on Wednesday. They were there “doing some inspections,” he added.

“Iran does have an obligation to accept our safeguards because they are signatory to the Nuclear Non-Proliferation Treaty,” Grossi added, “so they have an obligation.”

That treaty is known as the NPT. It’s the official, international, legally binding non-proliferation framework, and Iran is still a signatory. One of the options Iran reportedly has on the table if sanctions are reimposed is to walk away from the NPT.

Iranian Foreign Ministry spokesman Abbas Araghchi told Iranian state media that inspectors were allowed to monitor fuel being replaced at Bushehr. That was permitted by a decision of Iran’s Supreme National Security Council, Araghchi said, but he denied any new cooperation was agreed upon with the IAEA.

Fallout from recent conflict

The US has also been directly involved in the fighting. It has repeatedly said that it does not want war, but American forces did join the battle in the closing days and struck three sites in Iran.

Iran’s nuclear facilities in Natanz and Fordo were among the sites Israel bombed in June, which then led to a 12-day war between Israel and Iran. Iranian missiles and drones retaliated, hitting Israeli cities for the first time and sending hundreds of thousands of Israelis to shelters.

In July, IAEA inspectors left the country, saying it had become too dangerous during wartime to monitor the facilities. Satellitie imagery later showed several entrances to Iran’s Isfahan Nuclear Technology Research Center had been damaged.

Iranian officials accused the IAEA of enabling Israel’s strikes by releasing information that it was not in compliance with safeguards in the NPT. By publicizing that, Tehran officials said, the IAEA was giving Israel a pretext to attack.

Divisions inside Iran

Iranian parliamentary member Kamran Ghazanfari was one of a number of critics to say that allowing IAEA inspectors back in certain locations was a mistake.

“The recent remarks by the Parliament Speaker Mohammad Bagher Ghalibaf about entering a part of Iran’s Natanz site to the agency’s inspections, is an explicit violation of the laws made by parliament, which have suspended the cooperation with the IAEA,” Ghazanfari tweeted Wednesday.

Iran’s parliament had passed a law in July after the conflict, which was cast as a response to foreign aggression against Iran’s people and technology, as well as what lawmakers saw as bias by the IAEA in how it characterized Iran’s non-compliance.

Diplomatic window closing

European negotiators met with Iranian counterparts in Geneva on Tuesday. It was a last-ditch effort to try to avert sanctions.

But sources briefed on the meetings said little progress had been made. As tensions built in the days before the war, US envoy Steve Witkoff had been leading diplomatic efforts to try to get a new deal on Iran’s nuclear program. Those talks ended with the start of the fighting.

Grossi said Wednesday that in the next 30 days, “hopefully there will be a de-escalation,” but admitted, “I don’t know.” He pointed out that even if the process is triggered, “there is still a month” for things to change. “Many things could happen,” he added.

In the meantime, Iran is coming under more pressure from the West, and also from within. With the snapback mechanism’s expiration date looming, the next few weeks will likely make or break whether diplomacy can be salvaged from the pieces.