UN sanctions were reimposed against Iran on Saturday night over what western powers say is Tehran's failure to adhere to a 2015 treaty regulating the country's nuclear energy programme.
Britain, France and Germany launched the process at the UN last month to reinstate the sanctions, saying Tehran was in breach of its commitments.
Known as the “snapback mechanism”, this procedure means the reintroduction of a raft of restrictions that could deal a blow to an already struggling Iranian economy.
What sanctions have been reimposed?
Sanctions that have been reinstated include an embargo on the export of conventional arms to Iran, along with a ban on Tehran carrying out any activity with ballistic missiles capable of delivering nuclear weapons. A ban on any transfer to Iran of ballistic missile technology is also included.
Iran is also facing a complete ban on uranium enrichment and reprocessing. The country has previously been permitted to enrich uranium to a low level of 3.67 per cent for a civilian nuclear programme. The question of enrichment had been at the heart of negotiations with the US in June that were brought to an abrupt end by the Israel-Iran war.
In the economic sphere, the sanctions include a freeze on selected Iranian assets around the world and a travel ban on Iranian individuals and entities. Countries are authorised by the UN to inspect shipments carried by Iran Air Cargo − the cargo branch of flag carrier Iran Air − and the Islamic Republic of Iran Shipping Lines.
Why did the Europeans trigger the snapback?
Under the Joint Comprehensive Plan of Action reached between world powers and Iran in 2015, Iran agreed to limit uranium enrichment to levels necessary only for civilian nuclear power, in exchange for economic sanctions being lifted. The UN's International Atomic Energy Agency was tasked with monitoring Tehran’s nuclear programme.
The snapback mechanism’s purpose was to swiftly reimpose all pre-deal sanctions without being vetoed by UN Security Council members, including permanent members Russia and China, in the event that Iran was non-compliant.
The process began last month, when Britain, France and Germany − known as the E3 − formally notified the UN Secretary General Antonio Guterres and the UN Security Council president that they were triggering the procedure.
That began a 30-day window during which a new resolution to continue sanctions relief for Iran had to be adopted to avoid the reimposition of the restrictions. Last-ditch efforts to do so have failed.
The US was unable to activate the snapback because US President Donald Trump withdrew Washington from the nuclear deal in 2018.
The E3 said Iran had not adhered to the 2015 deal. They said Iran must resume negotiations with the US over its nuclear programme, allow in UN nuclear inspectors and account for more than 400kg of highly enriched uranium that the IAEA says it possesses.
They allege that Iran has “wilfully and publicly departed” from the nuclear deal’s commitments.
A number of countries suspect Iran is pursuing nuclear weapons, a charge that Tehran denies. In May, the IAEA said Iran had amassed 408kg of uranium enriched up to 60 per cent purity. If it is enriched to 90 per cent, it would be enough to make nine nuclear weapons, according to the UN agency, though a weapon would require other expertise, such as a detonation device.
The amount of enriched uranium far exceeds the limits set out in the 2015 nuclear deal. In addition, in 2022, Tehran removed most monitoring equipment, including IAEA cameras, from its nuclear sites. A year later, Iran barred some of the watchdog's most experienced inspectors.
The view from Iran
Iran has long maintained that its nuclear programme serves peaceful purposes only. Tehran also argues that it has the right to abandon the nuclear deal’s limits because Washington withdrew from the agreement and reimposed its own sanctions.
Tehran contends there is no legal basis for the Europeans to reimpose the UN sanctions, claiming the countries failed to uphold the accord after the US exit.
Iranian Foreign Minister Abbas Araghchi has said the revival of sanctions is “null and void” and carries no legal force. He told the Security Council that the US and its European allies bore full responsibility for any fallout from their decision.
“The developments we have witnessed set a dangerous precedent,” he said. “If agreements can be broken at will, no nation can trust international commitments.
“If unlawful measures are enforced by power instead of law, the Security Council risks losing credibility and authority.”

