European firms that cut ties with Iran over new US sanctions which kicked in at Midnight might find themselves subject to sanctions of their own, warned an EU official.

“If EU companies abide by U.S. secondary sanctions they will, in turn, be sanctioned by the EU," Nathalie Tocci, an aide to the EU’s foreign policy chief Federica Mogherini, told BBC Radio 4 on Monday, according to NBC News.

The EU is helping Iran "In order to signal, diplomatically, to the Iranians that Europeans are serious" about trying to salvage the Iran nuclear deal - which President Trump pulled out of in May, sending former US Secretary of State John Kerry running around Europe and the UN to try and nurse his baby back together.

At midnight Monday, the U.S. began targeting oil-rich Iran's automotive industry and civil aviation sector, as well as trade in gold and other metals in a set of punitive measures that had been eased under Trump’s predecessor, Barack Obama. Trump has called for a wholesale overhaul of Iranian regional policies, such as an end to its military support for the Syrian government and regional militant groups like Lebanon's Hezbollah. The 2015 pact did not curb these actions, one reason Trump has called the agreement "the worst deal ever." -NBC News

Early Tuesday morning, President Trump tweeted "Iran sanctions have officially been cast," adding "Anyone doing business with Iran will NOT be doing business with the United States. I am asking for WORLD PEACE, nothing less!"

The Iran sanctions have officially been cast. These are the most biting sanctions ever imposed, and in November they ratchet up to yet another level. Anyone doing business with Iran will NOT be doing business with the United States. I am asking for WORLD PEACE, nothing less! — Donald J. Trump (@realDonaldTrump) August 7, 2018

German car manufacturer Diamler announced on Tuesday that it had halted its activities in Iran.

“We will continue to closely monitor the political developments, especially in connection with the future of the nuclear agreement,” the company said in a statement.

And in June, Peugeot's parent company PSA took steps to suspend a joint-venture in Iran, while rival Renault also agreed to follow the US sanctions.

French oil giant Total has said it would quit a multibillion-dollar gas project if it cannot secure a waiver from the sanctions — a request the French government says had been rejected. -NBC News

The move follows comments made in May by US Ambassador to Germany, Richard Grenell, who warned firms against continuing to do business with the Islamic Republic or risk consequences.

“U.S. sanctions will target critical sectors of Iran’s economy. German companies doing business in Iran should wind down operations immediately,” he tweeted.

As @realDonaldTrump said, US sanctions will target critical sectors of Iran’s economy. German companies doing business in Iran should wind down operations immediately. — Richard Grenell (@RichardGrenell) May 8, 2018

International inspectors, meanwhile, say Iran has been complying with the nuclear deal to cut back its nuclear program as the US prepares to reimpose the remainder of sanctions lifted in the agreement - targeting Iran's oil sector and central bank.

America has also pressured allies to stop importing oil from Iran before the November deadline. Top buyers of Iranian oil include China, India, Turkey and South Korea. The effects on Iran of Washington's hardening stance have been stark, with Iran's rial currency losing two-thirds of its value in six months. -NBC News

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As a reminder, on Tuesday, following an executive order signed by Trump, the U.S. imposed new restrictions intended to stop the purchase of dollar banknotes by Iran, prevent the government from trading gold and other precious metals and block the nation from selling or acquiring various industrial metals. The measures, which took effect at midnight in Washington, also targeted the auto industry and banned imports of Persian carpets and pistachios to the U.S.

There were some signs Trump's aggressive policy was already working. Yesterday, Iran's President Hassan Rouhani, under rising economic and political pressure, spurned President Donald Trump’s suggestion for talks with “no preconditions.” However, in a televised address on Monday night, Rouhani also said Iran is open to negotiations if the U.S. is “sincere,” but he added that such talks would be meaningless while his nation is being hit with sanctions. Trump and his top aides have raised the possibility of face-to-face discussions with Rouhani with “no preconditions.”

“Negotiations at the same time as sanctions, what meaning does that have?” Rouhani said. “It means someone is facing a person who’s a rival and enemy, if they use a knife and they stick the knife in their arm and then they say, ‘Let’s negotiate and let’s talk.’ The response to this is first all, they have to take the knife out and put the knife back in their pocket.”

Rouhani also scoffed that despite his offer for talks, Trump “is someone who, without any negotiation, has withdrawn from all of his international commitments,” from trade accords to the Paris climate agreement.

Iran’s Foreign Secretary Javad Zarif tweeted that the “Trump Administration wants the world to believe it’s concerned about the Iranian people. Yet the very first sanctions it reimposed have canceled licenses for sales of 200+ passenger jets under absurd pretexts, endangering ordinary Iranians. US hypocrisy knows no bounds.”

At the same time, Europe condemned Trump's action saying it would block their effect for European companies. “We deeply regret the re-imposition of sanctions by the U.S., due to the latter’s withdrawal from the Joint Comprehensive Plan of Action (JCPOA),” according to a statement Monday from the foreign ministers of the U.K., Germany, France and the European Union. “Preserving the nuclear deal with Iran is a matter of respecting international agreements and a matter of international security.”

Meanwhile, in an attempt to halt its sharp economic deterioration, Iran’s central bank scrapped most currency controls introduced this year on the eve of the U.S. move, in a bid to halt a plunge in the rial that has stirred protests against the government. As Bloomberg reports, under the measures, Iran's central bank will let the market determine the rate of foreign-exchange transactions except the imports of essential goods and drugs, Governor Abdolnaser Hemmati told state television Sunday night. Licensed currency houses whose trading had been halted will be allowed to resume operations from Tuesday.

But the policies backfired, with the rial weakening from 40,000 at the start of the year, to more than 100,000 to the dollar on the black market this month.