VIENNA -- Iran and the United States reacted positively Tuesday (April 6) to the opening exchanges in a first day of talks in Vienna aimed at reviving an international agreement on Tehran's nuclear programme.
The landmark 2015 agreement, known as the Joint Comprehensive Plan of Action (JCPOA), reached between Iran, the United States, China, Russia, Britain, France and Germany, was negotiated to ensure that Iran never developed a military nuclear programme.
But Tehran has repeatedly breached the terms of the deal and the US withdrew from it.
"I can say that overall, the meeting was constructive," the head of the Iranian delegation, Abbas Araghchi, said in a video on Iranian broadcaster Irinn.
On Wednesday, Iranian president Hassan Rouhani described the talks as positive, saying that "a new chapter" has begun in efforts to revive the JCPOA.
The European Union is acting as an intermediary between the United States and Iran, with Russia and China also participating directly in the talks.
"We do see this as a constructive and certainly welcome step," US State Department spokesman Ned Price said of the talks.
"It is 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 stringent limitations under the 2015 deal, and as a result what we might need to do to return to compliance ourselves," he added.
The talks between the delegates from the remaining members of the 2015 agreement will resume Friday in Vienna, a diplomat familiar with the discussions said.
Russian envoy Mikhail Ulyanov said Tuesday's meeting had been "successful", adding that negotiations will "take some time".
The ultimate goal of the JCPOA is to prevent Iran from pursuing a military nuclear programme. But Tehran has actively breached the terms of the deal through enriching uranium at higher purity levels and stockpiling it.
Just yesterday, ISNA quoted Behrouz Kamalvandi, spokesman for the Atomic Energy Organisation of Iran (AEOI), as saying that mechanical testing of an IR-9 prototype centrifuge has begun. That centrifuge would enrich uranium 50 times faster than the IR-1 that is allowed under the accord.
Back in January, the International Atomic Energy Agency (IAEA) said Iran had notified it that it was advancing research on uranium metal production, aiming to provide advanced fuel for a research reactor in Tehran.
As part of the nuclear deal, Iran had agreed to a 15-year ban on "producing or acquiring plutonium or uranium metals or their alloys".
Iran also announced in January it had started the process to enrich uranium to 20% purity at its underground Fordow facility.
Iran has been repeatedly warned against provocation as the US has made it clear that Tehran must comply with the contents of the JCPOA and stop the Islamic Revolutionary Guard Corps (IRGC)'s regional support for proxy militias.
Following Iran's temporary agreement with the International Atomic Energy Agency (IAEA) in February, US Army Central Command (CENTCOM) commander Gen. Kenneth McKenzie said Iran must refrain from any provocation as diplomatic efforts to salvage the 2015 nuclear deal with Tehran continue.