The U.S. State Department downplayed expectations for indirect talks that begin on Tuesday in Vienna on Washington and Tehran resuming compliance with the 2015 Iran nuclear deal, saying it expected the talks to be difficult.

“We don’t underestimate the scale of the challenges ahead. These are early days. We don’t anticipate an early or immediate breakthrough as these discussions, we fully expect, will be difficult,” State Department spokesman Ned Price told reporters during his daily briefing on Monday.

Iran’s foreign ministry said on Saturday that Tehran wants Washington to lift all sanctions and rejects any “step-by-step” easing of restrictions.

The comments came as France called on Iran to show a constructive stance in the indirect talks with the U.S. in the Austrian capital, which will be part of broader negotiations.

Iranian foreign ministry spokesman Saeed Khatibzadeh said that Tehran opposed any gradual easing of sanctions.

“No step-by-step plan is being considered,” Khatibzadeh told state broadcaster Press TV. “The definitive policy of the Islamic Republic of Iran is the lifting of all U.S. sanctions.”

Former president Donald Trump pulled Washington out of the nuclear pact in 2018 and reimposed sanctions on Tehran, prompting Iran to violate some of the accord’s nuclear restrictions.

Trump’s successor Joe Biden wants to revive the agreement but Washington and Tehran have been at odds over who should take the first step.

The U.S. State Department has said the focus of the Vienna talks will be on “the nuclear steps that Iran would need to take in order to return to compliance” with the nuclear accord.