Iran said Sunday its arch-foe the United States was "isolated" after a US unilateral declaration that UN sanctions are back in force against the Islamic republic was dismissed by other major powers.
The Trump administration said the so-called "snapback" of the sanctions was in effect and threatened to "impose consequences" on any UN member state that fails to comply.
"The United States is very, very isolated in its claims," Iran's foreign ministry spokesman Saeed Khatibzadeh said. "The whole world is saying nothing has changed."
The sanctions in question were lifted in 2015 when Iran and six world powers -- Britain, China, France, Germany, Russia and the US -- reached a landmark nuclear deal known as the Joint Comprehensive Plan of Action.
But US President Donald Trump withdrew from the JCPOA in 2018, saying the deal -- negotiated by his predecessor Barack Obama -- was insufficient. He also renewed and even strengthened Washington's own sanctions.
The US insists it is still a participant in the agreement that it walked out of, but only so it can activate the snapback option, which it announced on August 20.
Virtually every other Security Council member disputes Washington's ability to execute this legal pirouette, and the UN body has not taken the measure any further.
On Sunday, two permanent council members -- France and Britain -- issued a joint statement along with non-permanent member Germany saying the US's "purported notification" was "incapable of having any legal effect".
Russia also said the US lacked legal authority.
"The illegitimate initiatives and actions of the United States by definition cannot have international legal consequences for other countries," said its foreign ministry.
- 'Reckless actions' -
Iran brushed off the move and called on the rest of the world to unite against what it called the US's "reckless actions".
"This is all much ado about nothing, and I imagine these are the most bitter days and hours for" the United States, said Khatibzadeh.
"Tehran's message for Washington is clear. Return to the international community, to your commitments, stop rebelling and the world will accept you."
US Secretary of State Mike Pompeo announced Washington's latest move in a statement.
"Today, the United States welcomes the return of virtually all previously terminated UN sanctions on the Islamic Republic of Iran," he said.
Pompeo promised measures would be announced in the coming days against "violators" of the sanctions to ensure that "Iran does not reap the benefits of UN-prohibited activity".
With around six weeks to go until the November 3 US election, Trump could unveil those measures in a speech at the UN General Assembly on Tuesday.
Iran issued a stark warning if the US follows through with the measures.
"If the United States acts on these threats, directly, or with the cooperation of a handful of its puppets, it will face a serious response and be responsible for all the dangerous consequences," its foreign ministry said.
It added that Washington, by leaving the nuclear deal, has "explicitly denied itself of any rights" to use the mechanisms in agreement and UN Resolution 2231, which enshrined the nuclear accord.