Iran has amassed more low-enriched uranium than permitted under its 2015 nuclear deal with major powers, a UN watchdog has confirmed.
It is the first major step in violation of the deal since the United States pulled out of it more than a year ago.
The International Atomic Energy Agency (IAEA), which monitors Iran’s nuclear programme under the deal, confirmed in Vienna that Tehran had breached the limit.
The step could have far reaching consequences for diplomacy at a time when European countries are trying to pull the United States and Iran back from the brink of war, less than two weeks after Washington aborted air strikes at the last minute.
Europe opposed last year’s decision by President Donald Trump to abandon the nuclear deal signed under his predecessor Barack Obama, and pleaded with Iran to keep within its parameters.
Iran has said it aims to do so but cannot do so indefinitely, as long as sanctions imposed by Trump have deprived it of the benefits it was meant to receive in return for accepting curbs on its nuclear programme under the deal.
Foreign Minister Mohammad Javad Zarif said Iran had passed the threshold, exactly as it had warned it would: “We have said very transparently what we will do.”
Iran announced in May that it would speed up production of enriched uranium in response to the Trump administration sharply tightening sanctions that month.
Washington has now effectively ordered all countries to halt all purchases of Iranian oil or face sanctions of their own, which Tehran calls “economic war” designed to starve its population.
In the two months since the US sanctions were tightened, the confrontation has taken on a military dimension, with Washington blaming Tehran for attacks on ships, and Iran shooting down a US drone. Trump ordered air strikes in retaliation, only to abort the strikes minutes before impact.
Enriching uranium to a low level of 3.6% fissile material is the first step in a process that could eventually be used to produce the more highly enriched uranium that can be used to build a nuclear warhead. Iran has always denied it has any plans to build a weapon.
The nuclear deal imposes limits both on how much enriched uranium Iran can hold and on how pure those stocks can be.