U.S. and Iranian officials are calling talks in Vienna productive as the two sides and the other signatories of a 2015 agreement on Iran's nuclear program work to revive the deal.
U.S. State Department spokesman Ned Price said there is no expectation of direct negotiations for now, but that the United States is "open to them because we are open to diplomacy."
He said the meetings in Vienna are a "potentially useful step as we seek to determine what it is that the Iranians are prepared to do to return to compliance" with the agreement, which limited Iran's nuclear program in exchange for sanctions relief.
The United States withdrew in 2018 under then-President Donald Trump, a move that included enacting economic sanctions against Iran.
In response, Iran began taking steps away from its commitments as it sought relief from the sanctions, including holding larger stockpiles of enriched uranium and enriching the material to higher levels.
The two sides have each signaled a willingness to return to full compliance, but not a desire to take the first step.
Iran's Deputy Foreign Minister Abbas Araghchi called Tuesday's opening of talks a "constructive meeting."
Iranian President Hassan Rouhani added Wednesday in comments at a Cabinet meeting that the talks represent a "fresh chapter" and that all parties involved recognize that the agreement, known as the Joint Comprehensive Plan of Action, is the only way forward.