The United States has reimposed oil and financial sanctions against Iran, significantly turning up the pressure on Tehran in order to curb its alleged missile and nuclear programmes.
The move on Monday will restore US sanctions that were lifted under a 2015 nuclear deal negotiated by the administration of President Barack Obama, and add 300 new designations in Iran's oil, shipping, insurance and banking sectors.
Iran's President Hassan Rouhani vowed to break the sanctions imposed on Tehran's vital energy and banking sectors.
"America wanted to cut to zero Iran's oil sales ... but we will continue to sell our oil ... to break sanctions," Rouhani told economists at a meeting broadcast live on state television on Monday.
Ministry of Foreign Affairs spokesman Bahram Qasemi told state TV that the new sanctions are part of a psychological war launched by Washington.
"[US President Donald] Trump's administration is addicted to imposing sanctions ... America's economic pressure on Iran is futile and part of its psychological war against Tehran," Qasemi told a weekly news conference.
Meanwhile, US Secretary of State Mike Pompeo said the sanctions are intended to convince Iran to "abandon its current revolutionary course".
"The Iranian regime has a choice: it can either do a 180-degree turn from its outlaw course of action and act like a normal country or it can see its economy crumble," said Pompeo.
"We hope a new agreement with Iran is possible but until it makes changes in the 12 ways that I listed in May, we will be relentless in exerting pressure on the regime.
"Rest assured, Iran will never come close to getting a nuclear weapon on President Trump's watch," said Pompeo, adding that 19 rounds of sanctions have so far been imposed during the Trump administration.
Also on Monday, the Belgium-based SWIFT financial messaging service announced it was suspending access for some Iranian banks "in the interest of the stability and integrity of the wider global financial system".
The US government has previously told SWIFT that it is expected to comply with US sanctions and it could face sanctions if it fails to do so.
Al Jazeera's Zein Basravi, reporting from Tehran, said the strong talk coming from Iran was a defence strategy.
"Many Iranians we speak to tell us consistently that they have come to learn the only language the US understands is the language of strength."
"The Iran sanctions are very strong; they are the strongest sanctions we have ever imposed. And we will see what happens with Iran, but they're not doing very well, I can tell you," he said.
'Worst ever' agreement
Trump announced in May that his administration was withdrawing from what he called the "worst ever" agreement negotiated by the US and reimposed a first round of sanctions on Iran in August.
Other parties to the deal, including Britain, France, Germany, China and Russia, have said they will not leave.
The Foreign Ministry's Qasemi said Iran is in constant contact with other signatories of the nuclear deal that saw most international financial and economic sanctions on Iran lifted in return for Tehran curbing its disputed nuclear activity under UN surveillance.
"We are in regular contact with other signatories of the nuclear deal ... setting up mechanisms to continue trade with the European Union will take time," Qasemi told a weekly news conference in Tehran.
China, India, Italy Japan, Greece, South Korea, Taiwan and Turkey - all top importers of Iranian oil - are the eight countries granted temporary exemptions from the sanctions to ensure crude oil prices are not destabilised, US Secretary of State Mike Pompeo announced on Monday.
Anger in Iran
Earlier, thousands of Iranians rallied to mark the anniversary of the seizure of the US embassy during the 1979 Islamic Revolution.
Addressing the rally in Tehran on Sunday, Iran's military chief, Major General Mohammad Ali Jafari, warned Trump against overreaching when dealing with Iran.
"I want to say something to America and its weird president," Jafari said.
"Never threaten Iran, because we can still hear the horrified cries of your soldiers in the [desert] … and you know it better, how many of your old soldiers in American society commit suicide every day because of depression and fear that they suffered in battlefields.
"So, don't threaten us militarily and don't frighten us with military threats," he added.
Over the past year, Tehran has accused Trump of waging "economic warfare" and devastating its economy.
In his speech, Jafari assured the crowd that Trump's attacks on Iran's economy were a desperate attempt to defeat the republic and were doomed to fail.
But his optimistic tone stood in stark contrast to the widespread economic chaos Iran has endured during the past 12 months, including a nosedive in the value of its currency, a shake-up of President Hassan Rouhani's economic team - which saw several senior ministers dismissed - and nationwide protests against price increases and dire economic conditions.
Based on the figures from the Organisation of the Petroleum Exporting Countries (OPEC), Iran's petroleum exports hit $52.728bn in 2017. Its crude oil exports stood at 2,125,000 barrels per day during the same year, while its natural gas exports reached 12.9 billion cubic metres.
Those numbers, however, have already dropped in the current year.
In India, for example, crude oil imports from Iran dropped from 690,000 barrels per day in May to around 400,000 barrels per day in August, Vandana Hari, a Singapore-based global oil market analyst, said.
Iran's energy sector accounts for up to 80 percent of the country's income from exports, according to the US Energy Information Administration, so a disruption could bring serious pain to its financial bottom line and its people.
Aside from the energy industry, others outfits and activities being sanctioned include:
- Iran's port operators and shipping industry, which is also linked to the transport of oil and gas.
- Petroleum-related products and transactions from Iran.
- Transactions by foreign financial institutions with Iran's central bank and other banking institutions.
- Insurance and reinsurance institutions, which insure tankers that transport oil and gas.
- US-owned or controlled corporations with business activities with Iranian government and individuals.
- Individuals, whose named were previously removed from the sanctions list, could also be included.
- Iran-related SWIFT transactions could also be flagged.
US Sanctions [Al Jazeera]