Hawzah News Agency –The White House is trying to inject new impetus into talks with Iran to revive the 2015 nuclear agreement, saying that it will be impossible to return to the accord if a deal is not struck within weeks.

"Our talks with Iran have reached an urgent point," White House spokesperson Jen Psaki told reporters, noting that the US special envoy for Iran, Rob Malley, had returned to Vienna for indirect talks with Iran on both sides resuming compliance with the pact.

"A deal that addresses the core concerns of all sides is in sight, but if it's not reached in the coming weeks, Iran's ongoing nuclear advances will make it impossible for us to return to the JCPOA," she said.

In 2018, under the Trump administration, the US pulled out of the agreement, officially known as the Joint Comprehensive Plan of Action (JCPOA), on the grounds that it failed to rein in Tehran’s support for regional proxies.

Iran maintained compliance with the accord for a few months before it began rolling back its commitments in 2019 and enriching uranium.

US President Joe Biden entered the White House promising to re-enter the agreement. And in recent weeks US and western officials have said the two sides appeared close to reaching a deal.

Psaki's attempt to inject urgency into the talks echoed those of senior US officials who have tried to keep the momentum going as talks with Iran drag on.

On 21 January, US Secretary of State Antony Blinken said the negotiations had entered "a decisive moment”, and on 14 January the top US diplomat said the US had just “a few weeks left” to salvage the deal.

Looking to close in on an agreement, the Biden administration last week waived sanctions on some of Iran’s civilian nuclear activities.

With the two sides appearing to come closer together, opponents to reviving the accord have become more vocal.

On Tuesday, more than 30 Senate Republicans sent a letter to Biden saying that unless he gave Congress a voice in deciding whether to return to the Iran nuclear deal, they would attempt to block the move.

Last week, the top Senate Democrat on the Foreign Relations Committee, Robert Menendez, who opposed the original 2015 deal, said he was “concerned” over the current round of negotiations, as he warned some US officials were "clinging" to the framework of the 2015 nuclear agreement for "nostalgia's sake”.