Diplomats will gather again Tuesday at the historic Palais Coburg for discussions on sanctions, the EU’s chief nuclear envoy, Enrique Mora, told reporters.

“The new Iranian delegation recognizes the work we have done over the past six rounds and the fact that we will be building on that work to go ahead,” Mora said. “I feel positive we can be doing important things for the next weeks to come.”

The Islamic Republic’s lead negotiator, Ali Bagheri Kani, described the decision to move immediately on to sanctions removal as “a significant achievement,” adding he was “optimistic” after the first day in Vienna. He was accompanied by a delegation of some 40 people, the semi-official Khorrasan newspaper reported Sunday, including mid-ranking officials from the oil ministry and central bank.

Iran has said the discussions must secure full, guaranteed and verifiable removal of U.S. sanctions — including on its critical oil exports — and a commitment that Washington will never seek to leave a restored pact, as then-President Donald Trump did in 2018.

The U.S., having all but collapsed the deal when the Trump administration quit the accord, wasn’t in the room with the EU and envoys from Russia and China. But it took part indirectly through EU mediators, and

U.S.-Iran Nuclear Talks Restart Amid Pessimism: Analysts’ Voices

White House Press Secretary Jen Psaki said the U.S. continues to seek a “mutual return to full compliance” with the nuclear deal, though American officials have repeatedly said Iran should drop expectations that the Biden administration make a commitment that future presidents won’t decide to quit the deal again.

U.S. officials have also played down expectations of progress, stressing deep concerns over the extent to which advances in Iran’s nuclear knowledge can be effectively unwound.

Iran Wants Verifiable Sanctions Removal, Envoy Says Before Talks

In response to Trump’s sanctions, Iran significantly expanded its nuclear program by ramping up uranium enrichment to 60%, just below what’s needed to build a nuclear weapon. Iran has always denied a military dimension to its atomic program but western fears it would pursue a bomb drove diplomacy that culminated in the 2015 deal.

Tehran has also curtailed access for inspectors from the United Nations International Atomic Energy Agency to various sites and facilities.

The U.S. assault on the 2015 deal triggered a security crisis in the Persian Gulf and beyond, raising tensions between Iran and its two main regional rivals, Israel and Saudi Arabia.

Israel, a long-standing critic of the nuclear deal, accused Iran of “playing for time” in order to keep advancing its atomic work in comments by Minister of Foreign Affairs Yair Lapid as he visited London on Monday.

In Saudi Arabia, a senior official said all members of the six-nation Gulf Cooperation Council were following the talks very closely. While they supported restoring the 2015 deal as a first step, larger issues of regional security and stability, including Iran’s missile program, should also be addressed, the official said.

–With assistance from Arsalan Shahla, Golnar Motevalli, Kitty Donaldson, Donna Abu-Nasr and Jennifer Epstein.