TEHRAN - The recent proposal by the US National Security Advisor Jake Sullivan for an "interim deal" with Iran on the country's nuclear program seeks to "soften" Iran's demands and conditions in the upcoming talks, said Hossein Askari, an Iranian economist and the emeritus professor of business and international affairs at the George Washington University.

Sullivan raised the idea in a recent meeting with his Israeli counterpart Eyal Hulata, arguing that it will allow the parties to the talks to "buy more time for nuclear negotiations", western media reported Wednesday.

However, the rationale behind the proposal, according to the sources, is to put brakes on Iran's advancements in its nuclear program, such as pressuring Iran to freeze "enriching uranium to 60 percent of purity", in exchange for "release of some frozen Iranian funds".

In an interview with Iran's Mehr News Agency released on Sunday, Askari said the contours of the 2015 Iranian nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), have changed over the past years, as "it is no longer the P5+1 along with the European Union".

The JCPOA was originally sealed between Iran and the P5+1 group, namely Britain, China, France, Russia, the United States and Germany, in June 2015.

However, with the exit of the United States from the deal in May 2018 under the administration of former President Donald Trump, the layout of the deal's participants was changed into the P4+1 group with the EU serving as an observer and mediator.

Askari noted that there have even been attempts to indirectly involve Israel and some Arab states in the deal.

"Israel is a de facto member ... and Saudi Arabia and the United Arab Emirates are trying to get more and more involved as well. As you may recall, France has even proposed that Saudi Arabia should become a participant," he said.

Negotiations are getting more complicated, since "Israel and its American allies are a de facto and open negotiator against Iran to prevent it from a partial, much less a full nuclear program", the Iranian economist added.

Beside the changes in the layout of the JCPOA's membership, Iran's nuclear program has also developed significantly over time.

Iran has gone far beyond the limits on its enrichment purity, stockpile of enriched uranium, and research and development (R&D) program stipulated in the deal, in reaction to the US unilateral withdrawal from the deal and imposition of old and new sanctions.

With these realities, "a full agreement may be out of reach. So a partial agreement (as Sullivan suggests) may be better than nothing" for the Americans, Askari said.

Given Tehran's three major demands: compensation for US withdrawal from the JCPOA, lifting all sanctions, and guarantee that the agreement would not be abrogated again by the US next administrations, Washington has understood that Iran will not bend to its wishes, he added.

Through an "interim deal", according to Askari, Biden seeks to give "Iranians a small bite of sanctions relief", and to provide the inspectors of the International Atomic Energy Agency (IAEA) with a better access to Iranian facilities.

With an interim deal, Washington does not need to "hurry back to the JCPOA as it was" and might put more pressure on Tehran to "moderate its principal conditions in a long run" and "soften Iranian demands", he said.

Iran and the world powers will restart their long-delayed talks over the revival of the JCPOA in the Austria's capital Vienna on Nov 29.

Experts from Iran and the P4+1 group, with the indirect involvement of the United States, will convene to discuss the lifting of anti-Iran sanctions and possible return of Washington to the accord.