The US and Iran say they will begin indirect talks to try to get both countries back into an accord limiting Iran's nuclear programme.
It comes almost three years after then-US President Donald Trump brought his country out of the deal.
The announcement marked the first significant step in efforts to return to the 2015 accord, which restricted the Iranian nuclear agenda in return for relief from American and international sanctions.
President Biden came into office saying that a return to the deal was a priority. However, both countries have disagreed over Iran's demands that sanctions be removed first.
The restart of negotiations is tabled for Tuesday in Vienna.
White House press secretary Jen Psaki said the "diplomatic road ahead may be long, as it was during the first negotiations.
"We are very clear-eyed about the hurdles that remain.
"These talks will be structured around working groups that the EU is going to form.
"The primary issues that will be discussed are the nuclear steps that Iran would need to take in order to return to compliance."
Donald Trump's decision in 2015 was part of a "maximum pressure" campaign of increased US sanctions and other tough actions.
In response, Tehran stepped up its uranium enrichment and construction of centrifuges, while continuing to insist its nuclear development was for civilian and non-military purposes.
Agreement on the talks came after the European Union helped to broker a virtual meeting of officials from the UK, China, France, Germany, Russia and Iran, which remain in the accord, known as the Joint Comprehensive Plan of Action.
Jen Psaki continued: "We don't anticipate presently that there will be direct talks between the United States and Iran through the process though we certainly remain open to them."
In a tweet, Iranian Foreign Minister Javad Zarif said the aim of the Vienna session would be to "rapidly finalize sanction-lifting and nuclear measures for choreographed removal of all sanctions, followed by Iran ceasing remedial measures".
Cover image: Library picture of Iranian President Hassan Rouhani (Picture: PA).