This week's nuclear talks in Vienna "met expectations" but did not assuage U.S. doubts about Iran's willingness to negotiate in good faith over the 2015 nuclear deal, a senior State Department official told reporters on Friday.

The state of play: Iran refused to meet directly with the U.S. but held three days of talks with the nuclear deal's other signatories, while the U.S. — represented in Vienna by Iran envoy Rob Malley — communicated indirectly through envoys, primarily from the European Union.

• The talks are expected to continue in a similar format starting the middle of next week, the State Department official said.

Why it matters: President Biden promised on the campaign trail to return to compliance with the deal by lifting sanctions if Iran reversed its breaches of the nuclear elements of the deal. The Vienna talks are the most significant step yet toward kickstarting that process.

• Two working groups are now discussing the steps that both sides would have to take.
• But the talks will be “heading toward an impasse” if Iran continues to insist that the U.S. lift all sanctions imposed on Iran under former President Trump, including those not linked to its nuclear program, the State Department official said.
• Between the lines: The U.S. has said some of Trump's sanctions will stay on, while those that violate the deal or deprive Iran of the benefits it stood to gain from it will be lifted.
• Another issue is sequencing, with Iran continuing to insist that the U.S. make the first move.

What they're saying: “The United States team put forward some very serious ideas, demonstrated a seriousness of purpose," the senior official said. "It remains to be seen whether that seriousness of purpose is matched by Iran."

• As to Iran's refusal to meet directly, the official said: “We think it would be better if we could sit down with the Iranians. We’re not going to pay a price for that, so if they don’t want to meet with us, too bad.”

What to watch: Iran will hold its National Nuclear Technology Day on Saturday, which typically includes a new announcement on the nuclear program. Any news will offer a "clue into Iran’s thinking," the official said, and potentially "cast doubt on their intentions."