The European parties to the 2015 Iran nuclear deal are threatening Tehran with a “snapback mechanism” that would reimpose UN sanctions on the Islamic Republic. Iran has warned it will withdraw from the Non-Proliferation Treaty if the UK, France and Germany (the E3) attempt to revive the sanctions.

A Financial Times report published on Tuesday cited a letter from the E3 to the UN threatening to reimpose the snapback sanctions should Tehran refuse to resume talks related to its nuclear energy program. “We have made it clear that if Iran is not willing to reach a diplomatic solution before the end of August 2025, or does not seize the opportunity of an extension, [the E3] are prepared to trigger the snapback mechanism,” it said.

The snapback mechanism was included in the Iran nuclear deal – formally known as the Joint Comprehensive Plan of Action (JCPOA) – as a way to reimpose sanctions on Tehran if it attempted to weaponize its nuclear program or breach the international safeguards regime. Under the agreement, US, EU and UN sanctions were lifted in exchange for strict limits on Tehran’s civilian nuclear program.

The UN’s nuclear watchdog, the International Atomic Energy Agency (IAEA), had verified that Tehran was in compliance with the agreement on 11 separate occasions by the time Trump unilaterally exited the pact and reimposed all US sanctions in 2018.

In response to the US economic war and Israeli attacks on its nuclear program – including a wave of assassinations targeting Iranian scientists going back more than a decade – Tehran has broken the limits on uranium enrichment imposed by the JCPOA, but has not attempted to develop a nuclear weapon.

American and Iranian officials engaged in several rounds of dialogue earlier this year aimed at establishing a new nuclear agreement. Those talks were scuttled when Israel launched an unprovoked war on Iran in June. Trump joined Israel and ordered attacks on Iran’s nuclear facilities during the so-called ’12-Day War.’

Since the end of the bombing campaign, Tehran has said it would only engage in talks with Washington if it received assurance that the US and Israel will not restart the war during the diplomatic process. Trump has threatened several times to do just that if Tehran does not agree to a new deal.

While Iran has engaged in direct talks with officials from the E3, the country’s foreign minister explained that the discussions are pointless. “With the Europeans, there is no reason right now to negotiate because they cannot lift sanctions, they cannot do anything,” Abbas Araghchi said. “If they do snapback, that means that this is the end of the road for them.”

Iranian Deputy Foreign Minister Kazem Gharibabadi warned that if the snapback sanctions were implemented, Iran would retaliate, potentially including a withdrawal from the Non-Proliferation Treaty.