Talks on reviving the 2015 Iran nuclear deal will resume on November 29, according to the country’s top nuclear negotiator, as Western concerns about Tehran’s nuclear advances grow.

“We agreed to begin negotiations aimed at removing unlawful and inhumane sanctions on November 29 in Vienna,” Ali Bagheri Kani wrote in a tweet, which was later confirmed in US and EU statements.

In April, Tehran and six world powers began to discuss ways to salvage the nuclear deal. It has deteriorated since 2018, when then-US President Donald Trump withdrew from it and reimposed sanctions on Iran, prompting Tehran to exceed mandated uranium enrichment limits the following year.

Negotiations have been stalled since the election of hardline Iranian President Ebrahim Raisi in June, and they are expected to resume in Vienna with a tough stance.

Because Iran refuses direct contact with the US, the six rounds of talks held so far have been conducted through intermediaries, primarily European diplomats, who have shuttled between US and Iranian officials.

US State Department spokesperson Ned Price said in Washington that the US hoped Tehran would return in good faith and ready to negotiate. Washington believed they should pick up where they left off in June.

“We believe it is still possible to quickly reach and implement an agreement on a mutual return to compliance with the JCPOA by resolving the relatively small number of outstanding issues at the end of June,” Price said at a news conference.

“We believe that if the Iranians are serious, we can accomplish this in a relatively short period of time.” (However,) this window of opportunity will not last forever, particularly if Iran continues to take provocative nuclear steps,” he added.

The pact, known as the Joint Comprehensive Plan of Action (JCPOA), required Iran to take steps to limit its nuclear program in exchange for relief from economic sanctions imposed by the United States, the European Union, and the United Nations.

Earlier on Wednesday, the secretary of Iran’s Supreme National Security Council suggested that talks to resurrect the deal would fail unless US President Joe Biden could guarantee that the US would not abandon the pact again.