The group said it was "concerned by statements from the Trump administration that it may be seeking to create a false pretext for accusing Iran of noncooperation or noncompliance with the agreement in order to trigger the reimposition of nuclear-related sanctions against Iran".
The International Atomic Energy Agency, or IAEA, has certified eight times that Iran is complying with the agreement, as has the US up to this point, although the Trump administration said Iran is violating the "spirit" of the deal.
But supporters hailed Thursday's move, in which the US Treasury announced new sanctions on non-nuclear issues even as Trump's administration grudgingly maintained sanctions relief.
Russian Federation and China have made clear they'd vehemently oppose any move to revisit the Iran deal, although USA officials are betting they'd acquiesce if European allies join in pressing for action.
Last month, shortly after Trump grudgingly certified the Islamic Republic as abiding by the deal, reports emerged that he was directing his aides to develop a case for why the regime violated the agreement come the next October deadline.
"We are not going to stand for what they are doing", Trump told reporters on Air Force One. Former President Barack Obama's administration, which negotiated the deal, did so in mid-January and Trump's administration did so again on May 17.
As officials have made clear for months, the White House is seeking ways to find that Tehran is not complying with the agreement.
Those remarks have led to intense speculation over what may transpire if Trump willfully attempts to unravel the deal, despite the assessment of IAEA investigators and America's own intelligence community that the Iranians are holding up their end of the bargain. "About time for U.S.to stop spinning and begin complying, just like Iran".
President Donald Trump has repeatedly criticized the deal, but has yet to pull out of it.
Tillerson said the USA still hasn't made a decision about Iran's compliance with the Joint Comprehensive Plan of Action, as it's required to do every 90 days. Such certification is needed by United States law every 90 days in order for the Congress to continue to withhold nuclear-related sanctions against Iran.
But first Trump must decide to extend sanctions relief to Iran under a separate clock.
"If the country (Iran) is supposed to continue [to implement the nuclear deal] with the other five countries [Britain, France, China, Russia and Germany], it will be in a way that our interests is protected", he noted. Those, however, aren't specifically covered in the nuclear agreement. "America's nouveau riche president or Congress adopt a new measure on Iran every day, which shows we shouldn't rely on the USA, and we don't need them after all", Velayati said.
Sherman warned against decertification, saying it would rob the USA of any leverage against Iran, drive a wedge between the US and its European allies, undermine American credibility in other negotiations such as on North Korea and NAFTA, and empower hardliners in Iran.
While the U.S. acts as the sole detractor of the landmark deal, the United Nations, the European Union and major world countries have defended the JCPOA and appreciated Iran's full compliance with it.
The current crisis with North Korea has been discussed often in this context - that tearing up the Iran deal would harm US credibility with North Korea as it tries to negotiate for Pyongyang to denuclearize.