The Trump administration called it the largest sanction the United States had ever taken against Iran. The Iranian president called it an act "Economic War" and said his country would win.
The package of heavy economic sanctions that the United States imposed on Iran on Monday is the most significant part of President Trump's decision last May to abandon the 2015 Iranian nuclear deal, which he described as a disaster.
The penalties include some gaping exceptions that could undermine their effects, including: Iran's biggest oil buyers, such as China and India, are not punished for at least six months.
However, the Iranian oil, shipping and banking sectors could suffer significant damage, and the weakened currency could continue to decline under sanctions, which, as Trump said, are intended to halt Iran's unacceptable actions in the Middle East.
Iranian President Hassan Rouhani, encouraged by widespread criticism of Mr. Trump's sanctions policy, including the United States' closest allies, was defiant on Monday. He said his country would not limit itself to the language of violence, pressure and threats and promised to break the sanctions.
While the outcome of the confrontation is unclear, experts said Iran and sanctions Iran's already battered economy will definitely feel more pain
"This will be much more difficult, if not impossible, for Iran in some areas," said Farhad R. Alavi, managing partner of the Akrivis Law Group, a Washington-based law firm specializing in sanctions and export laws. "Sales are falling and costs are rising."
Here are the basics of Iran's recent sanctions on Iran, Iran's response and what might happen next:
What did the United States do on Monday?
The Trump government has lived up to its promise to impose on Iran the most severe economic sanctions that have been relaxed or lifted under the nuclear deal negotiated three years ago by the United States and other world powers.
The government threatened to punish buyers of Iranian oil as part of the declared goal of reducing Iran's oil exports to zero. Fifty Iranian banks and subsidiaries, over 200 people and ships, Iran's national airline and more than 65 Iranian aircraft were blacklisted.
In the context of such sanctions, the United States may confiscate assets under its jurisdiction that are owned by blacklisted individuals and organizations. The sanctions also prohibit trade relations with these persons or entities.
What does Mr. Trump want from Iran?
The President argues that the nuclear agreement did not prevent Iran from acquiring nuclear weapons and wanted the restrictions imposed by the agreement to be permanent. He also wants Iran to give up its development of ballistic missiles and stop Supporting militant groups in Syria, Yemen and elsewhere who see the United States as a terrorist organization.
What does Iran say?
The Iranians accused the United States of duplicity and violations of international law because they had reached an agreement not only with Iran, but also with five other major powers, Great Britain, China, France, Russia and Germany. All are still supporting the agreement, and its validity has been reaffirmed in a United Nations Security Council resolution.
President Rouhani said his country would "proudly" break the newly imposed sanctions and that Iran had waged an "economic war" with the United States.
The Iranian military investigated the message of defiance in an extensive exercise hours after resumption of sanctions, new missiles as part of its anti-aircraft system.
Iranian Foreign Minister Mohammed Javad Zarif, an outspoken critic of Mr Trump, said the sanctions would be strengthened what he called the growing isolation of the United States,
Why did the US grant exemptions to Iran's oil exports?
The Trump government says it wants to deny Iran the revenue it receives from oil, the country's most important export export, but in a way that does not destabilize the world market. A total ban on Iran's oil exports could limit supply and peak prices – an outcome that Trump considers politically dangerous.
On Monday, Secretary of State Mike Pompeo announced that eight major oil importers – China, India, South Korea, Turkey, Italy, Greece, Japan and Taiwan – were re-sanctioned They would receive 180-day exemptions or waivers to buy Iranian oil as long as they saw a fall in the amounts.
More than 20 countries have already reduced their imports of Iranian oil, causing Iranian exports to shrink by around one million barrels a day, Pompeo said.
American officials would need a great deal of influence to get China and India, Iran's biggest customers, to cut off all their imports. Both nations have an enormous energy requirement. The Chinese leaders are outraged by the escalating trade war Mr. Trump has begun, and they are suspicious of the diplomacy that Trump is conducting with North Korea over its nuclear program.
In light of this, experts say, China and India are unlikely to stop all Iranian oil imports – even after the 180-day exemptions expire.
"I think the US has calculated that market stability and geopolitical relations have replaced interests in trying to cut Iranian exports," said Henry Rome, an Iran analyst at the Eurasia Group, one in Washington resident political risk advisory firm.
Did the oil sanctions affect prices?
The global oil market, having expected the Trump government to grant some exceptions, had no appreciable reaction to the announcement. Brent crude oil, an international benchmark, was little changed on Monday and ranged from $ 73 to $ 74 a barrel.
Ellen R. Wald, senior executive of the Atlantic Council's Global Energy Center, a Washington-based research group, said in a telephone press conference on sanctions that price increases could be further mitigated by additional supplies expected next year, including the United States States.
In this case, the government could "urge countries to further reduce Iranian imports and not see much influence on American consumers."
Why are the European allies angry?
Despite Mr. Trump's complaints about the nuclear deal, Britain, France and Germany see this as a success. The International Atomic Energy Agency, the United Nations observer, has repeatedly stated that Iran complies with the terms of the agreement.
Europeans are therefore angry that the United States is using its enormous economic clout to threaten European companies that want to do business with Iran. Many of them have left the country.
In general, Europeans fear instability in Iran, which could bring with them security problems and migrants, and they are worried that the United States is taking steps to destabilize the country.
The Europeans have tried one an alternative payment system with Iran that would circumvent US sanctions and enable them to do business without risking penalties from the United States. However, the system is not yet complete and the Americans have basically mocked the idea and warned that they could sabotage the system by simply adding it to their sanction list.
Are Iran's leaders worried about the turmoil in Iran?
Some speeches by Iranian officials have expressed concern. Farhad Dajpesand, Iranian economics minister, said this was probably the country's "most sensitive" period since the founding of the government after the 1979 Islamic Revolution.
Interior Minister Abdul Raza Rahmani Fazli pointed out that the recent wave of economic protests in Iran is a serious challenge. The protests were partly caused by the failure of the nuclear agreement, which provided the economic benefits promised by Rouhani, although corruption and mismanagement were also considered root causes.
Is the Iranian economy threatened with collapse?
The biggest critics of Iran may say that this is the case. This indicates a sharp decline in the value of the Iranian currency since Mr. Trump took office. But many Iranian analysts say the impact of the re-imposed sanctions is far from clear.
"There is a big difference between crisis and collapse," said Rome. "I think they are on the brink of a crisis. They will have a hard time getting enough food and medicines. But Iran has faced great challenges in the past. There is nothing we have seen that they are about to give up. "