John Kerry
John KerryReuters

Former U.S. Secretary of State John Kerry on Monday warned Congress that it would be "extraordinarily dangerous" for it to reject the 2015 Iran nuclear deal.

The comments by Kerry, who helped broker the Iran deal while serving under former President Barack Obama, follow President Donald Trump's decision last month to decertify Iran's compliance with the 2015 agreement.

Kerry told the Chatham House international affairs think tank in London, according to the AFP news agency, that Trump's decision "was clearly made without relevance to any fact whatsoever" and criticized the involvement of Congress.

"It's been flipped over to the Congress with instructions, you guys fix it. How the U.S. Congress, which wasn't part of the negotiations, which isn't certified to be part of the negotiations, fixes an agreement which is working is beyond me," he added.

"What President Trump regrettably has done by his invective against the deal, he's polluted the pool in a way that whatever Congress does is going to be interpreted as their effort to kill the deal through the back door," Kerry insisted.

He warned there was a "great danger" that Congress could act unilaterally to alter the deal, narrowing Iran's room for maneuver and "creating a downward spiral that becomes extraordinarily dangerous."

"It would be a gigantic, historic mistake when dealing with nuclear weapons to allow anyone's politics to get in the way and break apart an agreement that is preventing a country from pursuing a nuclear weapon," he said, according to AFP.

This is the second time in recent weeks that Kerry has criticized Trump's decision to decertify the Iran deal.

He warned in late October that Trump risked driving Iran towards nuclear proliferation if he cancels the deal.

Kerry claimed that the nuclear deal places Iran under tough restraints, including round-the-clock surveillance and tracking every ounce of uranium produced.

“We would notice an uptick in their enrichment, like that,” he said, snapping his fingers.

“And nobody that I know of with common sense can understand what the virtue is in accelerating a confrontation with the possibility that they might decide they want to break out and make it (a nuclear bomb) now instead of 10 or 15 or 25 years from now,” added Kerry, who said that if Iran violated the deal, UN sanctions would snap back into place.

Kerry's predecessor, Hillary Clinton, had previously warned that Trump's threat to pull out of the Iran nuclear accord is "dangerous", suggesting he is undermining the validity of the United States' promises to other nations.