Germany, France and the United Kingdom will likely “trigger” the reimposition of United Nations sanctions on Iran this week, three European officials told CNN Wednesday. The so-called “snapback” provision of the 2015 Iran nuclear deal could be activated as soon as Thursday.

The process would take 30 days, but European leaders are hoping to use that time to encourage Tehran to reengage in serious talks, open its facilities to inspectors, and take steps to meet its nuclear obligations.

Iran has threatened “severe retaliation” if the sanctions return, and the prospect raises the specter of further escalation in the Middle East after a round of fighting that ended last month.

Deadline for “Snapback” Looming

Snapback provision of the 2015 Joint Comprehensive Plan of Action (JCPOA), the Iran nuclear deal, allows members of the United Nations to reimpose their sanctions if Iran violates the agreement. The mechanism will expire this October.

Iran’s nuclear program has grown far beyond the limits of the JCPOA since former President Donald Trump withdrew the United States from the agreement. The Islamic Republic has long maintained that its nuclear program is peaceful, but inspectors have warned that its ability to enrich uranium is approaching weapons-grade levels.

“Iran has moved away from the JCPOA by a very wide margin,” Rafael Grossi, head of the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), said Wednesday. “Going back to the original JCPOA would be almost impossible.”

U.S. Secretary of State Marco Rubio, who met with his European counterparts this week, characterized the snapback as “a very powerful piece of leverage on the Iranian regime.”

Inspectors Return to Bushehr Plant

Iran’s parliament passed a bill last week that would end cooperation with international inspectors, but teams from the IAEA have recently begun returning to facilities in the country.

Grossi confirmed that inspectors were at the Bushehr nuclear power plant on Wednesday. The team was there to monitor a fuel replacement process, he said.

“Today we are inspecting Bushehr,” he said in Washington. “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. One of Tehran’s options reportedly includes withdrawing from the NPT in response to renewed sanctions.

Abbas Araghchi, Iranian foreign minister, said IAEA inspectors were monitoring the Bushehr facility because they had been “allowed” by a decision from the Supreme National Security Council. But he denied that it reflected a new “agreement” for new cooperation.

Impact from Fighting Last Month

Relations between Iran and the IAEA grew even more tense after Israel attacked Iran’s nuclear facilities in June. A 12-day conflict ensued, with Iranian missiles striking Israeli cities and the U.S. military firing on three Iranian sites in the final days of the conflict.

The IAEA withdrew its inspectors in July after the director general said it was unsafe for monitors to be in Iran during wartime. Satellite images later showed entrances at the Isfahan Nuclear Technology Research Center had been damaged.

Iran has also accused the agency of helping Israel make its case for its attack by publicizing Iran’s non-compliance with the safeguard rules.

Criticism Within Iran

The IAEA’s return has already drawn criticism from some in Iran’s parliament. Kamran Ghazanfari, a member of the Islamic Consultative Assembly, wrote on his official website that Speaker Mohammad Bagher Ghalibaf’s comments about limited inspections were an “explicit violation” of the laws passed to suspend cooperation with the agency.

Iran’s parliament approved the law last month, a week after the fighting. It was billed as a protection against foreign aggression and what was described as biased reporting from the IAEA.

A Final Chance at Diplomacy?

European negotiators met with Iranian officials in Geneva on Tuesday for what was described as a last chance to avoid sanctions. European officials say little progress was made in the talks.

U.S. envoy Steve Witkoff had been in diplomatic discussions with Iran leading up to the conflict in an effort to create a new nuclear agreement. He said last week that the diplomatic push continued through June and ended with the start of fighting.

The IAEA’s Grossi, who was in Washington for meetings on Wednesday, said he is optimistic that the next month could be one of de-escalation. “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.

Iran has already come under fire for its actions since the fighting last month. The European Union said this week that it was responding to calls from Tehran by sanctioning members of the Islamic Revolutionary Guard Corps that it said had carried out “attacks on protesters in Iran and Bahrain.” It did not specify the time period for those attacks.

For now, Iran faces pressure from its own members of parliament as well as the international community. The snapback mechanism will likely be triggered within days, and the next month may well determine whether diplomacy or sanctions and confrontation are the primary features of Iran’s nuclear chapter.