If Iran continues to upgrade its centrifuges and enrich uranium to higher and higher levels, "there will come a point where it will be very hard to return back to the standards set by the JCPOA," Antony Blinken said in a joint press conference with his French counterpart Jean-Yves Le Drian in Paris.
This "adds some urgency to this effort, but we haven't reached that point," Blinken added.
Representatives of the signatories of the Joint Comprehensive Plan of Action (JCPOA) have held six rounds of talks in Vienna to revive the deal by bringing the United States back into the agreement that it left in 2018. Washington is indirectly involved in the talks.
After the US withdrew and re-imposed sanctions, Iran walked back on its nuclear obligations under the deal and is now enriching uranium far above the limit set in the accord.
The sixth round of talks wrapped up last weekend with Iran's chief negotiator saying they are close to finalizing an agreement.
Blinken said that serious differences remain to be bridged before they can reach an agreement.
Le Drian said Tehran has some difficult decisions to make. "We expect the Iranian authorities to take the final decisions – no doubt difficult ones – which will allow the negotiations to be concluded," he said.
Tehran has repeatedly said the United States must lift all sanctions that were imposed in violation of the deal.
A seventh round of talks is expected to begin in a few days.
Last week, Iran elected a new president, Ebrahim Raisi, a hardline judge with a record of human rights abuses including a role in 1988 prison massacres. Asked by a reporter if Washington would lift sanctions on Iran without an investigation into the allegations against Raisi, Blinken said that restoring the nuclear deal is in the United States' interest irrespective of who is in power in Iran.
Iran with a nuclear weapon
