Talks between Iran and the world powers still adhering to the 2015 nuclear deal resumed Tuesday in Vienna with the goal of bringing the United States back into the agreement.
The fifth round of talks began a day after Iran and the United Nations' International Atomic Energy Agency agreed to extend a deal for monitoring Iran's nuclear activities for one month.
While the U.S. is not directly participating in the talks, the U.S. special envoy for Iran, Rob Malley, has been in Vienna for previous rounds and is in touch with representatives from participants Germany, France, Britain, Russia and China.
After a Tuesday meeting of the Joint Commission on the Plan of Action, the Russian delegate, Mikhail Ulyanov, said that a resolution was visible and these are "probably the final round of the Vienna talks."
"The participants expressed readiness to do their best to resolve the remaining outstanding issues and to complete negotiations successfully as soon as possible," he tweeted.
Deputy Foreign Minister Abbas Araghchi, the Iranian delegate to the talks, told Iran state TV that "good progress" has been made in the previous four rounds and that he hoped the fifth would be the last.
"There are still important issues that need to be fixed," he said. "We hope that we will be able to reach a final solution during these several days of negotiations."
Malley said the previous round was "constructive and saw meaningful progress."
"But much work still needs to be done," the U.S. envoy wrote Monday. "On our way to Vienna for a fifth round where we hope we can further advance toward a mutual return to compliance."
Through diplomats from other countries, Iran has been in indirect talks with the United States about reshaping the 2015 international nuclear deal to restrain Tehran's nuclear ambitions. Iran has said its nuclear program is for peaceful purposes.
Former president Donald Trump withdrew the United States from the pact in 2018, imposing new sanctions on Iran's oil, banking and shipping sectors. But U.S. President Joe Biden is looking to rejoin the pact.
Iranian President Hassan Rouhani said last week that the United States was ready to lift trade sanctions, although a senior Iranian official later contradicted him. European diplomats said difficult issues remained in the negotiations.
Iran has maintained that for it to return to the deal, the U.S. must first lift its sanctions, while the U.S. says Iran must first return to compliance with the deal's terms.
Iran has consistently breached the 2015 pact's restrictions on uranium enrichment, but Secretary of State Antony Blinken told CNN if both sides can return to the original deal, "we can use that as a foundation both to look at how to make the deal itself potentially longer and stronger — and also engage on these other issues, whether it's Iran's support for terrorism ... its destabilizing support for different proxies throughout the Middle East."
But he told ABC News, "The first thing that we need to do is put the nuclear problem back in the box."