U.S. President Donald Trump is facing a Friday deadline to decide how to proceed and the White House is due to make an announcement.
In October, Trump declined to certify that the agreement was in USA national security interests despite reports by the United Nations nuclear agency and others that Iran was abiding by the deal.
Scrapping the deal now would remove important existing constraints on Iran's nuclear program, and would leave the United States in a far weaker position to negotiate meaningful future limits on the program, said the US think tank report.
Officials familiar with the likely new sanctions say they will target specific Iranian people and businesses.
Aaron David Miller, a former US State Department adviser who now works with Washington-based think tank The Wilson Centre, said that whilst Trump talked tough on Iran, he was actually "risk averse" and would prefer to take the safer route.
A unilateral USA withdrawal from the Iran deal would be another blow to America's diplomatic credibility, which has already been damaged after its multiple "retreats" from the worldwide organizations and commitments previous year.
"The aim is to send a message to Washington that Iran is complying and that it is better to have the nuclear agreement than to isolate Tehran", one diplomat said. "We are in the process of trying to deliver on the promise he made to fix it". They have always opposed President Trump's Iran policy.
Tehran had pledged to rein in its nuclear program in return for some easing of those economic restrictions imposed on it by the U.S., the United Nations, and European Union.
Iran has been looking to Europe for support ever since Trump started to threaten the nuclear deal.
Reports indicate that Trump is expected to reluctantly extend the sanctions relief at the behest of his advisers.
At a time when Iranian citizens are demanding political, social, and economic dignity, the Trump administration is actively taking steps to worsen their lot. Trump's tweets are already being used by the regime to suggest that these protests are illegitimate and USA -sponsored, weakening their appeal inside Iran.
Another proposal would require snapback if Iran refuses a request from the International Atomic Energy Agency, the U.N.'s atomic watchdog, to inspect a military site not now being monitored. And according toCNBC, the Atomic Energy Organization of Iran specifically warned that it could increase uranium enrichment in response to a negative decision by the Trump administration. Iran hawks worry the IAEA, fearing a confrontation with Iran, won't even ask for such an inspection.
MARTIN: The deadline for reimposing these sanctions on Iran is tomorrow.
Six individuals briefed on the matter - two congressional aides, two administration officials and two outside experts - refused to speak publicly on the issue but said that Trump's decision is not yet official and is still subject to last-minute changes, the Associated Press reported.
Tillerson suggested during his interview with the AP on Friday that Trump was leaning toward allowing the deal to remain as is while Congress continues to work to address his outlined issues.