Iran, which carries out brutal repression at home and is said to be helping Russia in its war against Ukraine, is becoming an insurmountable challenge for Western powers keen to avoid a new nuclear power in the Middle East.

“We are in a delicate situation and an apparent impasse,” a French diplomat admitted ahead of Wednesday’s UN Security Council meeting on the alleged use of Iranian drones by Russian forces.

Despite Tehran’s renewed support for an increasingly isolated Moscow, the United States and European Union are still hoping for a resurgence of the 2015 deal aimed at curbing Iran’s nuclear program — even as the outlook dims.

“Iran’s domestic suppression and aggression in Ukraine have increased political costs for the West and reduced appetite for lifting sanctions on Tehran,” said International Crisis Group analyst Ali Vaez.

“But the West has no good options, because the only thing worse than a repressive regime killing its own people is a nuclear-armed one doing it.”

Iran has denied supplying Russia with cheap kamikaze drones that have been attacking Ukraine for weeks, despite European and American officials saying they have clear evidence, and on Thursday the European Union imposed fresh sanctions on the Islamic Republic.

Experts say the West is walking a fine line, recognizing the need to punish Tehran but not wanting to allow tensions to escalate to the breaking point.

“The Iranian government is denying the arms deliveries to limit the damage to the West,” said Clement Therme of the Institute for Iranian Studies in Paris.

But he said officials had quietly confirmed the deliveries, noting comments by Supreme Leader Ayatollah Ali Khamenei on Thursday mocking those who questioned the existence of Iranian drones just a few years ago.

The 2015 agreement, officially known as the Joint Comprehensive Plan of Action (JCPOA), gave Iran sanctions in return for curbing its nuclear program.

It has been in shambles since then-President Donald Trump withdrew the United States from it in 2018, but talks to revive it have been ongoing since 2021.

Iran’s crackdown on the most intense anti-government protests in years, sparked by the death of 22-year-old Mahsa Amini in police custody last month, further limits the West’s options.

“The bloody repression and the rapprochement between Tehran and Moscow pose a serious problem for the West,” said Farid Vahid of the Jean Jaures Foundation, a French think tank, stifling any hope of a new nuclear deal.

“Today it is completely unimaginable that an American and an Iranian official would sign an agreement.”

Despite decades of mutual distrust between Russia and Iran, both countries now see common interests in opposing the Western powers and their crippling sanctions.

“The Islamic Republic is banking on a new world order and the end of Western dominance,” said Vahid.

“It’s very ideological and doesn’t correspond at all to the aspirations of Iranian society, but it’s the reality.”

Vaez agreed that the Iran-Russia axis has “transformed from a tactical partnership to a strategic relationship.”

Tehran fears that “Russia’s weakening in Ukraine will deprive Iran of the only major power it can rely on,” he said, and would not allow that “at any price”.

Iran, which has also been accused of providing Russia with surface-to-surface missiles, could also see it as an opportunity to modernize its own military.

Several experts say Iran hopes to receive Russian Sukhoi SU-35 fighter jets and S-400 missile defense systems, which could boost its prospects of intervening in Middle East conflicts.

Washington and the EU see Iran’s arms delivery to Russia as a violation of the UN resolution approving the 2015 nuclear deal, but are reluctant to push Tehran any further from the negotiating table.

“Iran has truly become a pariah and the Russians, who have access to its top leadership, are no longer interested in helping the Americans bring back the nuclear deal,” Therme said.

“Diplomacy is doomed to fail.”

But for Vahid, that’s a position Western nations cannot take.

“If we accept that the JCPOA is dead, what do we do?” he said.

“Nobody has a plan B, and nobody wants to embark on a new military adventure in the Middle East.”