Secretary of State Mike Pompeo has warned that the United States will exert "relentless" pressure on Iran unless it behaves "like a normal country."
Pompeo made the comments on November 5, hours after Washington imposed sanctions targeting key sectors of Iran's economy following President Donald Trump's decision to withdraw the United States from the 2015 nuclear agreement between Iran and world powers.
Iran urged the United Nations to hold the United States accountable for the sanctions targeting its energy, shipping, shipbuilding, and financial sectors, branding the measures "illegal" and in violation of a Security Council resolution. Officials earlier struck a defiant tone, saying the country would "bypass" the U.S. measures.
Labeled by Trump as the "toughest ever," the sanctions took force early in the day as part of U.S. efforts to ramp up pressure on Tehran to "change its behavior."
Washington says the terms of the nuclear accord, under which sanctions against Iran were lifted in exchange for curbs on the country's nuclear activities, were not strict enough to prevent Iran from developing nuclear weapons. It also accuses Tehran of supporting militant violence in the region and other "malign" activities.
Iranian officials have denied the allegations.
Eight Oil Waivers
A statement from the U.S. Treasury Department said the sanctions targeted more than 200 individuals and companies in Iran's shipping and energy sectors -- including the Atomic Energy Organization of Iran and its 23 subsidiaries and associated individuals, as well as 50 Iranian banks and their subsidiaries.
Secretary of State Mike Pompeo vowed that Washington will be "relentless" in pressuring Iran and that the sanctions will accelerate the rapid decline of Iran's international economic activity.
As part of the round of measures, the White House has warned Iran's customers they must reduce their purchases of oil to zero or face U.S. penalties, although it has issued 180-day waivers to eight countries that will allow them to continue importing Iranian oil.
Pompeo said the temporary oil waivers had been granted to China, India, South Korea, Turkey, Italy, Greece, Japan, and Taiwan.
He said more than 20 countries had already cut their oil imports from Iran as a result of the sanctions, reducing Iranian exports by more than 1 million barrels.
Meanwhile, Treasury Secretary Steven Mnuchin said that despite granting the waivers, Washington will "aggressively enforce" the sanctions.
Mnuchin said he expected European countries to honor the U.S. sanctions against Iran. But he said there also are certain transactions, including humanitarian, that will be allowed.
In Belgium, the SWIFT bank-messaging system said it was suspending “certain Iranian banks' access" to its services, without mentioning the restored U.S. sanctions against Iran.
The service said in a statement that it had taken this "regrettable" step "in the interest of the stability and integrity of the wider global financial system."
Washington has told SWIFT it is expected to comply with the U.S. restrictions and it could face sanctions if it fails to do so.
Iranian President Hassan Rohani responded early on November 5 by saying in a speech on state TV that Iran was facing a "war situation."
Rohani also vowed that Iran will "proudly bypass" U.S. sanctions to sell oil.
"America wanted to cut to zero Iran's oil sales...but we will continue to sell our oil...to break sanctions," Rohani said.
Meanwhile, Iranian state television aired footage of air defense systems that are involved in two-day military maneuvers across northern Iran.
Hours earlier, Trump called the sanctions the toughest ever imposed by the United States against Iran.
"We'll see what happens with Iran. But they're not doing very well," he said, referring to the economic setbacks the country has already faced because of an earlier round of U.S. sanctions.
Iran's economy has been hit hard, with the country's currency, the rial, plummeting in value, leading to some street protests in Iranian cities.
Israeli Prime Minister Benjamin Netanyahu lauded the U.S. sanctions as "historic."
"Today is the day the U.S. under President Trump's leadership imposed extremely harsh sanctions on Iran, the harshest sanctions imposed on Iran since the effort to curb its aggression began," he said.
Israel has been a fierce opponent of the Iran nuclear deal, saying it didn't rein in Iran's regional military activities.
Meanwhile, China's Foreign Ministry said Beijing regretted the U.S. decision and said it stood with the countries that have vowed to keep the Iran nuclear deal alive despite the U.S. withdrawal.
Britain, France, Germany, Russia, and China, which also signed the nuclear deal along with the United States, insist Iran has abided by its commitments and say they are determined to save the agreement.