Germany, France, and the U.K. are on track to trigger the reimposition of U.N. sanctions on Iran, three European officials told CNN on Wednesday. The so-called “snapback” process is part of the Iran nuclear deal, the three countries helped negotiate in 2015, and could be triggered as early as Thursday. The process takes 30 days to go into effect, leaving little time for diplomatic maneuvering.

European leaders hope Tehran will use that time to come to the table for real negotiations, open its facilities to international inspectors, and take steps toward compliance. But Iran has threatened to retaliate violently if sanctions are reimposed, raising the possibility of more turmoil in a region already roiled by recent fighting. Snapback deadline approaches A mechanism under the 2015 nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA), allows member nations to restore U.N. sanctions if they determine Iran is in violation of the deal.

The ability to trigger snapback will expire in October. Iran has increased its nuclear capacity well beyond the boundaries of the JCPOA since former U.S. President Donald Trump pulled the U.S. out of the deal. Tehran maintains the program is peaceful, but both inspectors and analysts say its enrichment is approaching weapons-grade capacity.

“Going back to the original JCPOA would be almost impossible,” Rafael Grossi, head of the U.N. nuclear watchdog the International Atomic Energy Agency (IAEA), said on Wednesday. U.S. Secretary of State Marco Rubio, who met with his European counterparts on the matter this week, called the snapback “a very powerful piece of leverage on the Iranian regime.”

The IAEA has had inspectors in the country in recent days after Iran’s parliament passed legislation that ended all cooperation with the U.N. nuclear watchdog. But Grossi said teams were at the Bushehr nuclear power plant on Wednesday. “Today we are inspecting Bushehr,” he told reporters in Washington on Wednesday. “We are continuing the conversation so that we can go to all places, including the facilities that have been attacked.”

The IAEA’s safeguards are part of the Nuclear Non-Proliferation Treaty (NPT), which Iran is still a signatory to. According to one report, withdrawing from the NPT is one option Iran has on the table if sanctions are reimposed. Iranian Foreign Minister Abbas Araghchi said the Bushehr monitoring was to ensure fuel replacement at the plant after a decision by Iran’s Supreme National Security Council. He denied there was any broader new agreement to provide “new cooperation” with the IAEA. Conflict fallout The tensions have been high since Israeli forces struck Iran’s nuclear facilities in June, which set off a 12-day war.

Iranian attacks followed in response, targeting Israeli cities. U.S. forces later joined in the final days of the conflict, with three sites in Iran coming under attack. The IAEA withdrew its inspectors from the country in July, with Grossi saying it was “impossible to continue the verification activity” during wartime. Satellite photos later showed damage to entrances at the Isfahan Nuclear Technology Research Center. The IAEA said at the time that the agency was being used as a “shield” to keep foreign nuclear inspectors away from Iranian sites. Iran later accused the watchdog of giving Israel a pretext to attack by publicizing a lack of Iranian cooperation with safeguards. Iranian divisions.

At home, the decision to allow IAEA inspectors into some sites has been criticized. Parliamentary member Kamran Ghazanfari said comments made by Speaker Mohammad Bagher Ghalibaf endorsing limited inspections at Bushehr were an “explicit violation” of legislation passed by Iran’s parliament to end cooperation with the agency. Iran’s parliament passed the legislation in the days after the June conflict, which it said was a response to foreign aggression and a perceived double standard in IAEA reporting.

Diplomatic efforts Diplomatic efforts were ongoing through Tuesday in Geneva, where European negotiators met with Iran. European leaders had hoped to broker a deal to prevent snapback sanctions, but sources in those meetings told CNN little progress was made. U.S. envoy Steve Witkoff was in Geneva ahead of the Israeli attack in diplomatic efforts to hammer out a new nuclear agreement.

Those talks were interrupted by the fighting, and a follow-up meeting in Doha collapsed after the conflict began. Grossi remains hopeful that there may be de-escalation in the next month, though. “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.