LONDON — France, Germany and the United Kingdom triggered the process to reimpose sanctions on Iran at the United Nations Security Council on Thursday, according to two senior diplomats.

The group of countries — known as the E3 — argued that it has repeatedly tried to bring Tehran back to the negotiating table for talks on its nuclear program but that the Islamic republic continues to breach its obligations under a 2015 nuclear deal.

It comes ahead of a deadline mid-October that would see the possibility of imposing United Nations sanctions on Iran expire.

The three countries have now notified the presidency of the U.N. Security Council that they intend to activate the “snapback” mechanism in the 2015 agreement over Iran’s nuclear program, known as the Joint Comprehensive Plan of Action (JCPOA.)

A U.K. official, granted anonymity to speak about sensitive matters, said it was “not a decision that’s been taken at all lightly” and had followed “very intense diplomacy” over the last 12 months. A senior French diplomat said: “Our aim has always been to give a chance to diplomacy… But in the absence of any gesture from [the Iranians], we would have to re-establish sanctions.” 

Britain, France and Germany have decided to move due to what they argue is Iran’s non-cooperation with the International Atomic Energy Agency; current levels of recorded enrichment in Iran; and a lack of engagement from Tehran in trying to reach a diplomatic outcome.

The same British official specified that Iran was in “significant” non-compliance with the terms of the JCPOA, with an enriched uranium stockpile of more than 9000 kg, 45 times the prescribed limit.  

The three countries will now enter a 30-day process during which they will seek engagement with Iran on the Security Council while the possibility of an extension remains.  

However, if the Security Council does not adopt a resolution to continue the lifting of the resolutions on Iran, six previously agreed resolutions will come back into effect.

The U.N. sanctions in place before the 2015 deal include a conventional arms embargo, restrictions on ballistic missile development, asset freezes, travel bans and a ban on producing nuclear-related technology.

The French official said the IAEA “says it is no longer able to guarantee the peaceful character of the Iranian programme,” and “it is not impossible that there are clandestine [nuclear] sites.”

The same diplomat expressed hope that Iran would make concessions and restart negotiations in the 30-day timeframe that now opens at the United Nations. However, Iran has threatened to withdraw from the nuclear non-proliferation treaty (NPT) if snapback sanctions are imposed. 

Nette Nöstlinger contributed to this report.