Iran’s national security council secretary has echoed remarks by the foreign minister that “verifiable” lifting of sanctions by the United States is required for a nuclear agreement.

In a tweet on Saturday, Shamkhani said, “Real, effective and verifiable economic benefit for Iran is a necessary condition for the formation of an agreement.” Earlier in the day, foreign minister Hossein Amir-Abdollahian told reporters in Tehran that Iran must have guarantees of US intentions and lifting of “some sanctions” can serve this purpose.

Shamkhani also demanded that no agreement can restrict Iran’s “right to continue research and development” in the nuclear program, which can be interpreted as a maximalist demand.

Tehran has been occasionally demanding that US should first lift sanctions to show its “goodwill”, but Washington argues that any unilateral step to remove sanctions might not reciprocated.

Talks to revive the 2015 nuclear agreement known as JCPOA took a recess in late January in what diplomats said was a critical stage for the United States and Iran to make key political decisions. US chief negotiator Rob Malley told MSNBC on Friday that the two sides have not agreed on key issues, such as which US sanctions should be lifted and what it means for Iran to return to JCPOA.

Malley said that US is willing to lift “most sanctions” imposed since former president Donald Trump withdrew from the agreement in 2018, but some were imposed for “Iran’s behavior” and are not related to the nuclear issue.