Negotiations to revive the Iran nuclear deal are heading into their most delicate phase, European diplomats said after the latest round of talks ended in Vienna.
"We have continued to make progress and important parts of a future deal have now been fleshed out, but the most difficult decisions lie ahead. We have of course worked based on the principle of nothing is agreed to [until] all is agreed," the group of diplomats from Britain, France, and Germany, known as the E3, said in a statement.
"Together we understand that time is on nobody's side. Decision time is coming up. We will reconvene next week," they added.
Negotiators from the E3 and the other major powers that struck the 2015 nuclear deal with Iran have been meeting in working groups in the Austrian capital since early April, with the EU team overseeing indirect talks between Iran and the United States.
The agreement has been on hold since 2018 when then-U.S. President Donald Trump pulled Washington out of the pact and reimposed crippling sanctions on Iran’s economy.
In response, Tehran steadily has overstepped the agreement’s limits on its nuclear program designed to make it harder for the Islamic republic to develop an atomic bomb -- an ambition Tehran denies.
The most difficult questions remaining include which of its sanctions Washington would be willing to lift and how to permanently prevent Iranian nuclear facilities from being used for military purposes.
EU envoy Enrique Mora, chief coordinator of the talks, said on June 2 he believes a deal will be struck at the next round of talks.
"I am sure that the next round will be the one in which we will finally get a deal," Mora told reporters as the fifth round wrapped up.
The negotiators are under pressure to reach a renewal of the pact before Iran's June 18 presidential election, which is likely to usher in a hard-line president.
Iran's top nuclear negotiator said barriers to the revival of the deal were complicated but not insurmountable.
"Differences have reached a point where everyone believes these differences are not insolvable," Abbas Araqchi told Iranian state TV. "But the details are important and Iran's firm positions are important to be observed."
In Washington, State Department spokeswoman Jalina Porter told reporters the chief U.S. negotiator, Rob Malley, would be returning to Washington soon and suggested the talks were making slow headway.
"Some progress has been made," she told reporters but added, "This isn't going to be a quick or easy process."