CNN  — 

The latest round of talks aimed at salvaging the Iran nuclear deal adjourned on Friday, with parties involved in those discussions declaring they have reached the point where “political decisions” must be made.

According to officials involved in the discussions in Vienna, negotiators were returning to their respective capitals for consultations and are expected to return next week. US officials have repeatedly warned that the window for a return to the Joint Comprehensive Plan of Action (JCPOA) is rapidly closing.

“January has been the most intensive period of talks on a mutual return to full implementation of the JCPOA to-date,” a State Department spokesperson said Friday.

“Everyone knows we are reaching the final stage, which requires political decisions. Negotiators, including Special Envoy (Rob) Malley, are therefore returning to capitals for consultations,” the spokesperson said.

Enrique Mora, the top European Union negotiator at the discussions in Vienna, said in a tweet that “political decisions are needed now. Safe travels to all participants,” Mora wrote.

US officials have said as recently as Thursday that the window for a return to the deal, which the US abandoned under the Trump administration, remains open. Brett McGurk, a top White House national security official, said Thursday that parties are “in the ballpark of a possible deal” but that he will not put “odds on it.”

However, State Department spokesperson Ned Price said in a press briefing Thursday that “that window is closing.”

“It is becoming narrower and narrower. I don’t want to characterize precisely where we are beyond what you’ve heard us say during the course of this round, and that is to say that there has been some progress achieved,” he said. “But if we are to get there, that progress needs to outpace the speed with which Tehran’s nuclear program has moved forward, has advanced.”

Secretary of State Antony Blinken warned on Monday that “it is getting to the point where its breakout time, the time it would take to produce fissile material for a bomb, is getting down to a matter of a few weeks, and that in and of itself is something that should not be sustained over time.”

“We’re very, very close to the end of the runway on the ability to get back into this agreement because what’s happened is, is Iran has been moving forward on its program,” he said in remarks Monday.

Negotiators from the US and Iran have yet to engage directly in Vienna, instead communicating through the other parties to the deal.

Iran said Monday that it will not rule out direct talks if a “good agreement” and “strong guarantees” are reached.

During a phone call with UN Secretary General Antonio Guterres on Friday, Iranian Foreign Minister Hossein Amir-Abdollahian reiterated his “lack of trust in the White House” emphasizing the need for the US and Western negotiators to “adopt practical, tangible and verifiable measures … to achieve a lasting and reliable deal.”