Iran’s chief nuclear negotiator Ali Bagheri Kani arrives at Palais Coburg where closed-door nuclear talks with Iran take place in Vienna, Austria, February 8, 2022. Reuters/Leonhard Foeger

Diplomatic efforts to revive the Iran nuclear deal of 2015 came under intense pressure from multiple directions on Thursday, with the Iranian regime insisting it would not surrender its “defensive power,” Russia demanding exemption from international sanctions imposed over its invasion of Ukraine, and a bipartisan group of US legislators raising doubts over the content of a new deal in a letter to the White House.

Diplomats at the negotiations in Vienna warned that prospects for an agreement, regarded as imminent until this week, were fading. “We are very close to an agreement, but the window of opportunity is closing,” Anne-Claire Legendre, a spokeswoman for the French foreign ministry, said on Thursday.

However, a statement from the head of Iran’s Supreme National Security Council indicated that the differences between the two sides were widening. “US approach to Iran’s principled demands, coupled with its unreasonable offers and unjustified pressure to hastily reach an agreement, show that US isn’t interested in a strong deal that would satisfy both parties,” Ali Shamkhani said on Twitter.

“Absent US political decision, the talks get knottier by the hour,” he added.

In Tehran, the regime’s “Supreme Leader,” Ayatollah Ali Khamenei, pledged that Iran’s stance would not waver, during an uncompromising message delivered through state media channels.

“Suggestions to reduce our defensive power so as to appease the enemy are nothing more that naive and ill-advised,” Khamenei said on Thursday. “Over time, these flawed proposals have been rebutted, but if they hadn’t been, Iran would have now faced great threats.”

Meanwhile, longstanding Western concerns regarding both Iranian support for terrorist organizations and the full extent of the regime’s nuclear ambitions were given short shrift by Khamenei.

“Regional presence gives us strategic depth and more power,” he said. “Why should we give it up? Scientific progress in the nuclear field is related to our future needs, and if we give that up, will anyone help us in the future?”

Khamenei made no reference to the most immediate obstacle to an agreement — the Russian government’s demand that its extensive commercial and military ties with the Iranian regime be exempted from the crushing sanctions imposed on Moscow since its invasion of Ukraine. Trade between the two allies in 2021 was valued in excess of $4 billion, with Iranian President Ebrahim Raisi signing a trade agreement on an official visit to Moscow in January of that year.

Last Saturday, Russian Foreign Minister Sergei Lavrov inserted a new Russian requirement into the proposed deal, announcing that he had asked the Biden administration for “written guarantees at the minimum level of Secretary of State that the current sanctions process launched by the US will not in any way harm our right to free, fully-fledged trade and economic and investment cooperation and military-technical cooperation with Iran.”

Russia’s ambassador at the Vienna talks, Mikhail Ulyanov, reiterated Lavrov’s demand on Thursday. “We believe that all our trade and economic relations with Iran should be exempt from current or future EU or US sanctions,” he told reporters.

Ulyanov rejected the notion that Russia was manipulating the Iran talks with separate calculations concerning Ukraine. Calling the claim that Russia was trying to sabotage the talks a “dirty misinterpretation,” Ulyanov tweeted that “a number of parties need a little bit more time to finalize the deal. Russia has always been a driving force, not an obstacle in the course of the negotiations.”

The Vienna talks did not escape the notice of Russian President Vladimir Putin, as the invasion of Ukraine entered its 15th day. Addressing government ministers in Moscow on Thursday, Putin referred to the nuclear deal negotiations during a diatribe blaming the US for the rising energy prices that have resulted from the invasion.

In its zeal to squeeze Russia, Putin argued, the US was willing to relax sanctions on its other foes. “They are ready to make peace with Iran, immediately sign all the documents, and with Venezuela. They went to Venezuela to negotiate, but they should not have introduced these illegitimate sanctions,” he stated, according to the official TASS news agency.

In the US, Russia’s last-minute demands exacerbated the skepticism among some legislators regarding the wisdom of a revived deal. Former President Donald Trump’s administration withdrew the US from the deal in 2018, saying that its “rotten” provisions would not prevent Iran from weaponizing its nuclear program.

In a letter to President Joe Biden on Thursday, a bipartisan group of 21 congressional representatives raised a series of concerns that they said must be resolved before they would support a revived deal. Among the 16 issues the legislators highlighted were congressional oversight of an agreement with Iran, the amount of “breakout” time that would be available to Iran in the event of an agreement, and the possibility that Russia would benefit economically from an agreement.

“We will review any agreement closely, but from what we currently understand, it is hard to envision supporting an agreement along the lines being publicly discussed,” the letter stated. “As the State Department has often noted in reference to a nuclear agreement with Iran, ‘Nothing is agreed until everything is agreed.’ We hope that no agreement is finalized without additionally addressing these concerns.”