Tehran’s nuclear progress is “alarming” and its stockpile of enriched uranium has grown significantly, a senior US official said on Monday.
The “breakout time” – the time needed to obtain enough uranium enriched for use in weapons – has shrunk from a year to “a few months”, said the senior administration official, speaking on condition of anonymity to AFP.
Iran would then need to complete a number of additional steps, including building a nuclear device small enough to fit onto a ballistic missile, a process known as miniaturisation.
The US official said the US was keen to resume negotiations with Tehran and that Washington still believes diplomacy is the best path forward.
The US and the EU are keen to revive a variation of the 2015-18 “nuclear deal” in which the US relaxed most sanctions on Tehran in exchange for permitting UN inspections of research sites. Iran also agreed to set limits on its nuclear activities and for these to be monitored.
“We’re hopeful we can be back in Vienna [for talks] ... in a fairly short period of time,“ the official said.
On Monday, Iran’s foreign ministry said the new round of discussions could start early next month. The comment came just after Iran's foreign minister said Iran expects the US to unfreeze millions of dollars of Iranian assets.
The "ball is in Iran's court", Jennifer Gavito, deputy assistant secretary for Iran and Iraq at the State Department’s Bureau of Near Eastern Affairs, told CNBC on Tuesday.
US negotiators were ready to begin talks as soon as Iran gives the go-ahead, Ms Gavito said, clarifying that they've been told the Iranians will resume talks "very soon."
Any talk of lifting sanctions would have to take place within the framework of the Vienna talks, Ms Gavito said. She declined to discuss what sanctions relief the US may have offered the Iranians.
The country’s nuclear activity will be at the centre of talks between US and Israeli national security teams in Washington on Tuesday and Wednesday.
Israel’s national security advisor, Eyal Hulata, and his White House counterpart, Jake Sullivan, will join a meeting of the US-Israel Strategic Consultative Group, which comprises representatives of both countries’ diplomatic, military and intelligence agencies.
In 2018, Donald Trump withdrew Washington from international talks with Tehran on uranium enrichment, held in Austria. His successor, Joe Biden, is keen to resolve the stand-off diplomatically.
“The path in Vienna for negotiations does remain open,“ the senior US official said. “The Iranians are sending indications to a number of parties that they are preparing to come back to Vienna and, of course, we will have to see whether they reengage in that process constructively or not.“
Despite Israeli scepticism, the Biden administration believes “very strongly that the diplomatic path remains the best”, the official said.
But he also said the White House and Israel agree that Iran has made rapid advances since Mr Trump quit the international talks.
Tehran says it does not seek nuclear weapons, only an energy industry.
“We have a common assessment of the extent to which Iran’s nuclear programme has dramatically broken out of the box since the previous administration left the Iran nuclear deal,“ the official said.
“The breakout time, meaning stockpiles of enriched uranium and other ways to look at this, it’s gone from about 12 months down to a period of a few months. So, obviously, that’s quite alarming.”
The official said the US believes diplomacy will be “the best way to put a ceiling on the programme and roll back the gains that Iran has made in recent years“. But there is no movement to lifting sanctions and if diplomacy doesn’t work, “there are other avenues“.
“We think the onus right now is on the Iranian side,“ the official said.