The US Chairman of the Joint Chiefs of Staff, General Mark Milley, said that he does not support removing the Quds Force, the foreign arm of the Iranian Revolutionary Guard Corps (IRGC), from the list of foreign terrorist organizations.
"I believe the IRGC is a terrorist organization, and I do not support them being delisted," General Milley told the Senate Armed Services Committee.
The United States is considering removing the IRGC from its blacklist of foreign terrorist organizations in exchange for Iranian assurances that it will curb the elite force.
In an exclusive interview with NBC, Secretary of State Anthony Blinken said that the Revolutionary Guard is a terrorist organization.
Blinken refused to get into the details of the negotiations but said he was "not overly optimistic" at the prospects of actually getting an agreement to a conclusion in Vienna.
Later, a US State Department statement said that Blinken's consultations with his E3 counterparts in the European Troika, France, Germany, and Britain, addressed the Iranian nuclear file.
Blinken and his E3 counterparts discussed a common resolve to ensure Iran never acquired a nuclear weapon. They agreed that a diplomatic solution entailing a joint return to full implementation of the JCPOA is the "best outcome" but noted that they are prepared for other scenarios if necessary.
A group of Democratic members of the House of Representatives held a press conference to express their concerns about the US administration's return to the 2015 nuclear agreement.
Earlier this week, Tehran and Washington exchanged blame for the delay in negotiations in Vienna.
Likewise, officials from several participating countries, including Iran, have stated in recent weeks that the agreement is imminent, but it has not yet seen the light due to various obstacles.
Among the outstanding issues is Iran's demand to delist its IRGC, although Washington has repeatedly stressed that this will not mean, in any case, the lifting of sanctions against the organization.
Last week, reports stated that one of the primary conditions for removing the IRGC from the US list of terrorist organizations was for Iran to drop its policy to avenge the assassination of its top general, Qassem Soleimani.
Sources told the US RadioFarda that the US intelligence services have "detailed information about plans to target US officials whom Tehran accuses of being involved in the killing of Soleimani," which will hinder any attempt to delist the IRGC.
Iranian Foreign Ministry spokesperson Saeed Khatibzadeh said that Washington is responsible for the pause in talks between Tehran and world powers in Vienna to revive their 2015 nuclear deal.
"The US is responsible for the halt of these talks ... a deal is very much within reach," Khatibzadeh told a weekly news conference, adding that Washington should make a political decision for the deal's revival.
Tehran would "not wait forever," he warned.
Last week, Iranian Foreign Minister Hossein Amir-Abdollahian said that the EU official, Enrique Mora, had conveyed Tehran's proposals to Washington, stressing that the ball is now in the US court.
The US State Department blamed Tehran for making requests unrelated to the nuclear file.
Spokesman Ned Price said it was “unfair” to say that the ball is in US court, adding that "we still believe there is an opportunity to overcome our remaining differences."
Price warned that as soon as Iran's advancements in its nuclear program go beyond the nonproliferation benefits, "the deal would no longer be in our interest.
For months, negotiations have been taking place in Vienna between Iran on the one hand and China, Russia, France, the UK, and Germany on the other hand to revive the nuclear agreement.
The US is participating indirectly in the negotiations through an EU mediator.