Officials from world powers and Iran were meeting in the Austrian capital for the first time since March, when negotiations — which began in 2021 to reintegrate the United States into the agreement — stalled.

“Today’s talks in Vienna do not mark a new round of negotiations. These are technical discussions,” the three countries — known as the E3 group — said in a statement.

“The text is on the table. There will be no re-opening of negotiations. Iran must now decide to conclude the deal while this is still possible. We urge Iran not to make unrealistic demands outside the scope of the JCPoA,” or Joint Comprehensive Plan of Action, the statement said.

Russia’s envoy to the talks said on Friday they had resumed in a “serious” atmosphere even as few expect a breakthrough compromise while Tehran’s disputed uranium enrichment program surges forward.

Indirect talks between Tehran and Washington restarted in Vienna on Thursday with a meeting between the Islamic Republic’s chief nuclear negotiator Ali Bagheri Kani and European Union coordinator Enrique Mora.

After meeting Bagheri Kani on Friday, Russian envoy Mikhail Ulyanov was quoted by Iran’s state news agency IRNA as saying that reaching the finish line “may not be so easy, and time will tell whether we will succeed or not.

“But in general, the atmosphere of the talks is serious.”

White House national security spokesman John Kirby said on Thursday that the negotiations were “pretty much complete at this point.”

Bagheri Kani put the onus on the White House to compromise, tweeting that the United States should “show maturity & act responsibly.”

Foreign Minister Hossein Amirabdollahian said on Friday that for Tehran’s negotiating team, “Iran’s economic benefit from the deal, observing the country’s ‘red lines’ and preserving (our) indigenous nuclear capability and technology is of serious interest,” IRNA reported.

Britain, China, France, Germany, Iran, Russia and the US signed the JCPOA in July 2015.

But following the unilateral withdrawal of the US in 2018 under former president Donald Trump and the re-imposition of US sanctions, Tehran has backtracked on its obligations to curtail its atomic activities, such as uranium enrichment.

The UN’s nuclear watchdog, the International Atomic Energy Agency, has found that Iran subsequently exceeded the agreed enrichment rate of 3.67 percent, rising to 20 percent in early 2021.

It then crossed an unprecedented 60-percent threshold, getting closer to the 90 percent needed to make a bomb.

IAEA chief Rafael Grossi on Tuesday warned Iran’s program was “moving ahead very, very fast” and “growing in ambition and capacity.”

But Tehran argues that the issues “are political in nature and should not be used as a pretext for abuse against Iran in the future.”

“Now, the hours in Vienna are decisive and the Iranian side must be given assurances as soon as possible,” an Iranian diplomat told the Iranian state news agency, IRNA.