VIENNA — Russia’s invasion of Ukraine has cast a shadow over talks to revive the Iran nuclear deal, which extended beyond a presumed deadline Tuesday amid growing doubts that a new agreement is in sight.

Iran’s chief negotiator returned to Vienna from a visit to Tehran over the weekend with hardened demands, diplomats say, dampening hopes that an agreement to bring the United States back into the deal and Iran back into compliance would be wrapped up by the end of February. European negotiators had warned that they were prepared to walk away if there was still no agreement by Monday.

On Monday the United States joined the warning, with State Department spokesman Ned Price telling reporters in Washington that the Biden administration also is “prepared to walk away if Iran displays an intransigence to making progress.”

Iran’s Foreign Ministry spokesman Saeed Khatibzadeh countered Tuesday with a warning that Iran could pull out, too.

“Iran is willing but will not wait forever,” he said on his Twitter feed, adding, “A deal is at hand if WH [White House] makes its mind.”

“A no deal outcome is as possible as reaching a potential deal because some minimum demands of Iran remain unmet,” cautioned the official Iranian news agency IRNA.

The threats may just be part of the inevitable last-minute brinkmanship that typically accompanies the final hours of negotiations, analysts say. “The negotiations will probably get more turbulent in the coming days, exacerbated by Russia’s invasion of Ukraine, underscoring that the prospect of failure is real,” Henry Rome wrote in a note for the Eurasia Group.

But the stakes, always high, have been raised higher by the Ukraine war, which has rocked the stability of Europe, sent oil prices soaring and raised the specter of nuclear conflict for the first time in over 30 years.

 

Failure in Vienna would further destabilize the world, risking a new nuclear arms race in the Middle East and perhaps yet another war, analysts say.

“It could be a 1914 moment,” said Ali Vaez of the International Crisis Group.

A member of Austrian armed forces last month walks past Palais Coburg, where Iran nuclear talks are taking place in Vienna. (Leonhard Foeger/Reuters)

The concern is, he said, that Iran has been emboldened by the collapse of relations between the United States and Russia and the soaring price of oil to press for new concessions, on the assumption that high oil prices will make Washington more desperate for a deal. Russia is one of the seven original parties to the deal, along with the United States, Britain, France, Germany, China and Iran.

 

The Ukraine war has pushed the price of oil above $100, causing pain for consumers in the United States and around the world and putting pressure on politicians. The return to world markets of Iranian oil could bring prices down by as much as 10 percent, Vaez said.

 

After acting on many previous occasions to rescue the talks from collapse, Russia could also potentially become a spoiler now that its relationship with the West has ruptured, said Esfandyar Batmanghelidj of the European Council on Foreign Relations.

Reviving the deal nonetheless continues to make sense for all the parties concerned, including Russia, he said. Russian Ambassador Mikhail Ulyanov has repeatedly told reporters that the war has had no impact on the talks. He called it “regrettable but not dramatic” that the talks had not wrapped up by Monday.

 

“It was a timeline not a deadline,” he wrote on his Twitter account.

Negotiators have spent the past 10 months trying to hammer out an agreement on the terms under which the United States will return to the nuclear deal negotiated by President Barack Obama, known as the Joint Comprehensive Plan of Action, and bring Iran back into compliance. President Donald Trump’s decision to pull out of the agreement and impose tough sanctions on Tehran prompted Iran to renege on its promises to refrain from enriching uranium.

 

Iran’s nuclear program has now reached the point where it is only weeks away from achieving breakout, which would mean it has enough enriched uranium to produce a nuclear bomb, diplomats and experts say.

“It’s a really bizarre situation. We were finally at a point a couple of weeks ago where all the parties really believed a deal was at hand. And now the international environment has shifted,” said Batmanghelidj, who nonetheless added he believed a deal was more likely than not.