The United States vowed Monday to be "relentless" in countering Iran as sweeping sanctions took effect, but the Islamic republic defiantly promised to stand up to the "bullying" by Washington. President Donald Trump is administration nonetheless issued eight exemptions from its demand on all countries to stop buying Iran is oil, its largest export, amid widespread global opposition to the unilateral US sanctions.
Six months after Trump pulled out of an international agreement on ending Tehrans nuclear program, secretary of state Mike Pompeo said the ultimate US goal was for Iran to make a "180-degree turn" and abandon its "current revolutionary course."
While stopping short of urging regime change, he reiterated his demands for Iran to end policies rooted in the 1979 Islamic revolution including its support for regional proxies such as the Lebanese militia Hezbollah and its development of missiles.
"We hope a new agreement with Iran is possible, but until Iran makes changes in the 12 ways I listed in May, we will be relentless in exerting pressure on the regime," Pompeo said.
He said the sanctions -- which took effect on the 39th anniversary of Iranian zealots seizure of the US embassy following the ouster of the pro-US shah -- intended to "starve the Iranian regime of the funds it uses to fund violent activity throughout the Middle East and around the world."
UN inspectors say Iran is abiding by an agreement reached with Trumps predecessor Barack Obama to draw down its nuclear program. That deal was backed by European powers, Russia and China and sealed by a UN Security Council resolution.
"I announce that we will proudly bypass your illegal, unjust sanctions because its against international regulations," Irans president Hassan Rouhani said in a televised speech as the sanctions took effect.
"We are in a situation of economic war, confronting a bullying power. I dont think that in the history of America, someone has entered the White House who is so against law and international conventions," he added.
In one of Tehrans bazaars, there was anxiety over the future.
"The shadow of the sanctions has already affected the economy in a disastrous way, peoples purchasing power has plunged," said Ehsan Attar in his herbal remedy shop.
Act on your commitments
Rouhani said four countries had approached him during his visit to New York for the UN General Assembly in September offering to mediate with the US, but he turned them down.
"There is no need for mediation. There is no need for all these messages. Act on your commitments, and we will sit and talk," he said.
Irans ambassador to the United Nations, Gholamali Khoshroo, asked the world body Monday to hold the United States to account, although there was no indication that member-states would take up the issue.
The latest tranche of US sanctions aims to significantly cut Irans oil exports -- which have already fallen by up to one million barrels a day since May -- and cut off its banks from international finance.
The Belgian-based SWIFT banking network, the backbone for international monetary transfers, said Monday it had suspended several Iranian banks from its service.
The International Monetary Fund forecasts that US sanctions will cause Irans economy to contract 1.5 per cent this year and 3.6 per cent next year -- pain that Trump has boasted about as he touts his record ahead of Tuesdays congressional elections.
Irans economy was already suffering major structural problems -- including widespread corruption, weak investment and a banking sector laden with toxic assets -- before Trump walked out of the deal.
Rouhanis plan since his election in 2013 was to boost the economy by rebuilding ties with the world and attracting billions of dollars in foreign investment -- a strategy that now looks in tatters.
Exemptions to sanctions
The United States issued eight waivers to its ban on buying Iranian oil -- to China, India, Italy, Greece, Japan, South Korea, Taiwan and Turkey.
Trump said he wanted to go "a little bit slower" on oil sanctions to avoid a price hike, which is especially sensitive in the United States.
"Im not looking to be a great hero and bring it down to zero immediately," Trump told reporters, saying the move "would cause a shock to the market."
And despite Trumps repeated declarations that the Iran deal has been a "disaster," the United States announced exemptions that preserve civilian nuclear cooperation started under the accord.
The activities at Bushehr, Irans only nuclear power station, as well as the Fordow enrichment plant and the Arak heavy water reactor, will be allowed "to continue under the strictest scrutiny to ensure transparency and maintain constraints on Iran," a State Department statement said.
The other parties to the nuclear deal -- Britain, France, Germany, China and Russia -- have vehemently opposed the US move and vowed to keep alive the accord, technically known as the Joint Comprehensive Plan of Action.
The only support for the US position has come from Irans regional rivals, notably Saudi Arabia and Israel, whose prime minister, Benjamin Netanyahu, hailed the start of sanctions as "a historic day."
Foreign companies and banks are largely unwilling to make enemies of the US Treasury, and most international firms that set up in Iran after the 2015 deal have been forced to leave, including Frances Total, Peugeot and Renault, and Germanys Siemens.
"Unfortunately, we were treated dishonourably by both the American and Iranian governments," said Fereshteh Safarnezhad, a 43-year-old teacher, on the streets of Tehran.
"The Americans never really committed to the deal and the Iranian government did not spend the cash it got from the deal on the people."