By Sune Engel Rasmussen in Beirut, Laurence Norman in Brussels and Aresu Eqbali in Tehran
Iran said it will begin enriching uranium beyond limits set in a 2015 nuclear deal, marking the second intentional violation of the multiparty deal and putting it at risk of complete collapse.
Since President Trump pulled out of the pact last year, Tehran has warned it would step up nuclear activities in a bid to raise the pressure on Europe, China and Russia to provide relief from crippling U.S. economic sanctions and to raise costs to Washington of continuing its so-called maximum pressure campaign.
On Sunday, Iran said it would begin making technical changes at its nuclear facilities to start enriching uranium above the 3.67% allowed under the nuclear deal, and surpassing the limit by Monday morning -- a move that brings it a small step closer to having fissile material that could be used in an atomic weapon.
"Tomorrow early morning we will have passed over 3.67%," Behrouz Kamalvandi, spokesman for Iran's atomic agency, said in a press briefing in Tehran.
He didn't say to what level Iran would enrich uranium but said that it was to supply fuel to power plants, indicating Iran will initially only enrich at 5% purity.
"If the 3.67% becomes 3.68%, or 4% or 5%, it is not important. This has a political strategic significance," said Abbas Araghchi, Iran's deputy foreign minister and a key player in the nuclear negotiations.
Iranian officials said the latest decision wasn't meant to undermine the nuclear accord, but that it was up to the remaining parties to live up to their commitments.
A top adviser to Supreme Leader Ali Khamenei on Saturday had hinted that Iran would increase enrichment only to 5%. Iran has produced up to 20% enriched uranium in the past. Weapons grade uranium is 90%.
Last week, Iran also breached the nuclear deal's cap on its stockpile of low-enriched uranium.
Iran's brinkmanship could present President Trump, who has spoken out against U.S. involvement in Middle East conflicts, with difficult questions of war and peace as he prepares for the 2020 elections.
The U.S. on Friday summoned a special session of the board of the International Atomic Energy Agency to consider Iran's actions, which will take place on July 10. Washington may push for a formal censure of Tehran. The Vienna-based agency oversees Iran's obligations under the 2015 deal.
"The international community must hold Iran's regime accountable," the U.S. said in a statement on Friday.
A spokesman for the United Nations atomic agency said inspectors will be checking to see if Iran goes over the 3.67% limit.
"IAEA inspectors in Iran will report to our headquarters as soon as they verify the announced development," he said.
Sunday's statement dashed European hopes that Iran would move only gradually to breach the accord's limits. Some diplomats had initially hoped that Iran would take months to move clearly in violation of the agreement. Still, with Iran only increasing its uranium stockpile and enrichment levels gradually, it will strengthen those voices in Europe saying there is still time for diplomacy.
European officials have said they may trigger a dispute procedure in the 2015 accord if Iran continues to breach its obligations. That would start a weekslong process that could end with international sanctions being reimposed on Tehran.
Sunday's move marks the end of a 60-day deadline issued by Iran in May, when it said it would cease to abide by certain commitments under the nuclear deal if European nations didn't do more to help offset the economic impact of U.S. sanctions.
Mr. Araghchi said Foreign Minister Javad Zarif on Sunday sent a letter to European Union foreign policy chief Federica Mogherini stating the latest step and issuing another 60-day deadline to take further action, but he didn't disclose what those measures would be.
French President Emmanuel Macron spoke with Iranian President Hassan Rouhani on Saturday and said he was deeply concerned about Tehran's weakening of the nuclear accord, and "the consequences that would necessarily follow," according to a statement from the French president.
Messrs. Macron and Rouhani also agreed to explore by July 15 the conditions for a resumption of talks between the remaining parties to the nuclear agreement, the statement said.
Asked about the prospect of the U.S. joining in the talks, Mr. Araghchi said, "If the U.S. wants to take part in talks, on the condition of lifting its sanctions, it is possible in our view."
Tightened American sanctions have reduced Iranian oil exports by about 90%, causing severe ripple effects across the country's economy, and driving Tehran to adopt a more confrontational stance.
In addition to the nuclear activities, the U.S. has accused Iran of attacking oil tankers and Saudi oil facilities -- charges that Iran denies. In June, Iran shot down an American spy drone.
Once 5% enrichment is reached, the jump to 90%-enriched weapons-grade uranium is relatively straightforward.
Nuclear experts say somewhere around 200 to 250 kilograms of 20%-enriched uranium, when further enriched to 90%, is enough to fuel one nuclear weapon. In 2013, shortly before an interim deal was struck, Iran had produced 196 kilograms of the material. That stockpile was sent abroad or diluted into harmless material under the 2015 agreement.
Nonetheless, the steps Iran has taken so far don't significantly impact on Iran's breakout time -- how long it would take Tehran to produce enough fissile material for one nuclear bomb. The nuclear deal was crafted to ensure Iran's breakout time was at least a year.
Notably, Iran has steered clear of actions or threats to other key parts of the nuclear deal. Western diplomats say Iran has, for the most part, allowed timely inspections of nuclear-related facilities by the IAEA's monitors.
It has also, crucially, not threatened to disregard limits on the number and type of centrifuges it deploys to enrich uranium, a critical component of maintaining the one-year breakout time.
Under the deal, Iran was required to remove and place in storage two-thirds of its close to 20,000 centrifuges, most of which were basic machines of a type used decades ago in Western countries. Iran also placed in storage around 1,000 somewhat more advanced machines.
Were Iran to reinstall all its centrifuges or add more advanced ones, it could significantly reduce the time needed to produce a nuclear weapon to below one year, a threshold Trump administration officials say they are closely monitoring.
Iranian officials on Sunday said increasing the number of centrifuges wasn't necessary for now.
"We don't need to increase centrifuges," Mr. Kamalvandi said. "Adding centrifuges is an option the country's senior officials can choose."
Write to Sune Engel Rasmussen at firstname.lastname@example.org and Laurence Norman at email@example.com