Iran said on Monday it would only return to Vienna to finalize a deal to revive its landmark 2015 nuclear deal with world powers, with the final steps depending on Washington.

Tehran is engaged in long-running negotiations in the Austrian capital to relaunch the deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), with Britain, China, France, Germany and Russia directly, and the United States indirectly.

“We will not go to Vienna for further negotiations but to finalize the nuclear deal,” Foreign Ministry spokesman Saeed Khatibzadeh told reporters in Tehran.

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However, Iran said there were outstanding issues it was waiting for Washington to resolve.

“At the moment, we don’t have a definitive answer from Washington yet,” Khatibzadeh said.

“If Washington answers the outstanding questions, we can go to Vienna as soon as possible.”

The JCPOA granted sanctions relief to Iran in exchange for curbs on its nuclear program to ensure Tehran could not develop or acquire an atomic bomb – something it has always denied wanting to do.

But the United States’ unilateral withdrawal from the deal in 2018 under then-President Donald Trump, who reimposed biting economic sanctions that prompted Iran to start backtracking on its own commitments.

“Final phase”

The talks in Vienna aim to bring the United States back to the nuclear deal, including lifting sanctions against Iran, and to ensure Tehran’s full compliance with its commitments.

The Iranian and American delegations in Vienna do not communicate directly but through other participants and the European Union, the coordinator of the talks.

Nearly a year of negotiations have brought the parties closer to renewing the 2015 agreement.

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But the talks broke down last month after Russia demanded guarantees that Western sanctions imposed following its invasion of Ukraine would not harm its trade with Iran.

Russian Foreign Minister Sergei Lavrov later said that Moscow had received the necessary guarantees from Washington on trade with Iran.

Among the main sticking points is Tehran’s demand to remove the Islamic Revolutionary Guard Corps, the ideological arm of the Iranian military, from the US terrorist list.

Washington recently confirmed that sanctions against the guards would stand.

On Wednesday, the US Treasury announced action targeting several entities it accuses of being involved in procuring supplies for Iran’s ballistic missile program.

A day later, Khatibzadeh said Washington’s imposition of new sanctions on the Islamic Republic showed its “ill will” towards Iran.

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On Monday, Khatibzadeh directed further criticism at the United States.

“Today, in the final phase, the United States seeks to deprive Iran of the economic benefits of the agreement,” Khatibzadeh said.

On Sunday, however, Iranian Foreign Minister Hossein Amir-Abdollahian said a deal was “close”, in a phone conversation with UN Secretary-General Antonio Guterres.

“We have conveyed our proposals on the remaining issues to the US side through the EU’s chief negotiator, and now the ball is in the US court,” the Iranian foreign minister said.