Germany, France, and the United Kingdom are set to announce the triggering of the reimposition of United Nations sanctions on Iran as early as Thursday, three European officials told CNN on Wednesday. The so-called “snapback” mechanism, created by the 2015 Iran nuclear deal, gives those countries the option to reimpose those sanctions within 30 days.

That gives little time for diplomacy, and European leaders are hoping Tehran will use that time to reengage in serious negotiations, open its facilities to international inspectors and work toward compliance with its nuclear obligations. However, Iran has also threatened strong retaliation if sanctions are reimposed, with the risk of more violence for a region just emerging from months of conflict. IAEA inspectors were at Iran’s Bushehr nuclear power plant Wednesday, and more teams are expected to return to Iran this week.

Rafael Grossi, the head of the IAEA, confirmed their presence at Bushehr on Wednesday. “Today we are inspecting Bushehr. We are continuing the conversation so that we can go to all places, including the facilities that have been attacked,” he told reporters in Washington, DC. Despite the IAEA’s inspections process being embedded in the Nuclear Non-Proliferation Treaty (NPT) to which Iran is a signatory, Tehran has reportedly discussed withdrawing from the NPT as one of its options in the event sanctions are reimposed. “Iranian FM Abbas Araghchi on the visit of IAEA inspectors: The fuel replacement at Bushehr had already started when the Supreme National Security Council took a decision on the arrival of inspectors to monitor that process,” state media outlet IRNA tweeted Wednesday.

“Abbas Araghchi: “We have not made a new agreement with the IAEA on new cooperation.”” The conflict Iran and Israel are recovering from has increased tensions dramatically in recent weeks, as Israel struck Iran’s nuclear facilities in June. Iran retaliated by attacking Israeli cities, and in the final days of the 12-day conflict, U.S. forces also joined in, striking three Iranian sites.

The IAEA pulled out its inspectors in July, and later that month satellite images revealed entrances at Iran’s Isfahan Nuclear Technology Research Center had been damaged. Tehran blamed the IAEA for the Israeli strike, saying it had effectively given Israel a pretext by publicizing Iran’s non-compliance with safeguard rules. Tensions are also building internally. Kamran Ghazanfari, a member of Iran’s parliament, condemned Speaker Mohammad Bagher Ghalibaf’s comments on Sunday that inspections on limited sites would go ahead.

Ghazanfari called Ghalibaf’s remarks “an explicit violation” of Iranian laws suspending cooperation with the IAEA. That law was passed in parliament in the immediate aftermath of the Israel-Iran conflict in June.

At the time, Iranian lawmakers described it as “bolstering the armed forces and nation’s readiness in the face of the US and Zionist enemy plots and preventing espionage and information sabotage against the Islamic establishment and suspension of relations with the head of the IAEA.” The suspension was a reaction to what Tehran described as “false and malicious” IAEA reports that were biased and favored foreign powers. A Diplomatic Window Could Close On Iran Tensions by October The diplomatic window is likely to narrow further Thursday if, as expected, the Europeans trigger the snapback mechanism.

European negotiators spoke with Iranian representatives in Geneva on Tuesday in what was described as a last-minute effort to avoid sanctions. “We are running out of time for diplomacy with Iran. We believe our talks on the margins of the IAEA Board of Governors were helpful, but there are no guarantees. It is up to Iran whether it chooses to pursue de-escalation and dialogue, or a path of confrontation,” an EU official told CNN.

The IAEA’s Grossi said he was still hopeful. “Don’t forget that there is still time, even if there is the triggering thing, there is a month, and many things could happen. We have to wait and see,” he said. Until that process of diplomacy plays out, Iran is under pressure on multiple fronts. It had been engaged with U.S. envoy Steve Witkoff in the weeks leading up to the conflict on a diplomatic effort to forge a new nuclear deal.

Those talks have now collapsed, and with the 30-day window ticking down, European leaders are in a race against time to keep diplomacy alive. The snapback mechanism itself is also set to expire in October, giving Tehran even less incentive to take any sort of meaningful action.