The demonstrations continued to weigh heavily on Foreign Relations committee members' minds on Monday as Trump neared the deadline for the nuclear sanctions decision.

Officials had said that despite the recommendation of his entire national security staff, they weren't sure which way Trump would go.

"The threat of sanctions is a very real one - who wants to invest in Iran if you don't know what it going to happen in the future?" said Angela Kane, a German diplomat who was the United Nations high representative for disarmament. After working with the House, the Senate bill was rolled into the law signed by President Trump in August 2017, Countering America's Adversaries Through Sanctions Act, which included actions against North Korea and Russian Federation as well as Iran.

Mnuchin did not say when.

Instead of scuttling the agreement, a senior White House official said Trump wants Washington's European allies to use the 60-day period before sanctions relief again comes up for renewal to agree on tougher measures.

Trump had vowed to rip up the agreement during his election campaign and has repeatedly referred to it as "the worst deal ever", accusing Iran of violating the "spirit" of the pact. Trump has complained that numerous Iranian restrictions expire next decade and has vacillated between talk of toughening the deal and pulling the US out entirely. The US Congress requires the president to approve sanctions waivers related to the deal - signed by Iran, the US, the UK, Russia, France, Germany, China and the European Union -every 120 days.

MARTIN: All right. Ambassador Dennis Ross, a distinguished fellow at the Washington Institute, thanks so much for being with us this morning. "We have as many sanctions on Iran today as we have on any other country in the process". If they cannot reach an agreement, Congress could end the USA role in the JCPOA.

"Trump is unpredictable, but I guess you have to guess that he will do what he did last time, which was to send the problem to Congress", Steinberg said. "We need to wait and see, since we can not make a prediction". "The administration is continuing to work with Congress and with our allies to address those flaws".

The other signatories to the deal - Britain, China, France, Germany and Russian Federation - and the European Union, which oversaw the talks, were watching carefully.

Such a move would offer some relief in Europe, where leaders fear unilateral US sanctions on Iran could unravel the nuclear deal hammered out between Iran and six world powers. He called the agreement a "considerable diplomatic accomplishment". While noting that Iran has all options on the table, Velayati also expressed criticism of European countries: "Some of the allies of the United States insist on upholding the JCPOA, yet the United States acts differently".

Also addressing reporters, French Minister Jean-Yves Le Drian called the deal "essential", saying: "There is no alternative".

But global observers say Iran has been in full compliance with the deal. Mr Macron "reaffirmed France's determination to see the agreement strictly enforced and the importance for all of its signatories to abide by it", his office said.

The US Treasury said Larijani, the brother of Iran's parliamentary speaker and former nuclear negotiator Ali Larijani, is to blame for the torture and degrading treatment of prisoners. "The smooth implementation of the agreement should be accompanied by a stepped-up dialogue with Iran on its ballistic missile program and its regional policy in order to guarantee greater stability in the Middle East".

U.S. Secretary of State Rex Tillerson said last week that Trump would be inclined to authorize another sanctions waiver if he felt that real progress was being made toward the changes he demanded in October.

Also on January 8, another Iranian official, this time atomic chief Ali Akbar Salehi, issued a warning.

Trump said they included the deal's "sunset clauses", one of which allows for the lifting of restrictions on Iran's uranium enrichment programme after 2025.

It would defy other members of the United Nations Security Council, which backed the deal, as well as most USA allies.

"I don't think we should conflate the two", Goldstein said.