The US said international sanctions on Iran are automatically “snapping back,” in a move that most nations say the Trump administration doesn’t have the authority to demand since quitting a 2015 nuclear deal two years ago.

“Sanctions are being re-imposed on Iran,” secretary of state Michael Pompeo said in a statement late on Saturday.

“The United States expects all UN member states to fully comply with their obligations to implement these measures.”

That’s unlikely to happen, with key European powers on Sunday stressing their commitment to the nuclear agreement.

A chorus of opposition

Their support for the deal has left the US isolated on the United Nations Security Council, and most nations say America has no authority to demand the return of international sanctions, since it’s no longer a party to the deal.

“We have worked tirelessly to preserve the nuclear agreement and remain committed to do so,” the foreign ministers of France, Germany and the UK said in a statement on Sunday.

The accord is “a key pillar of the global non-proliferation architecture,” Josep Borrell, the European Union’s foreign policy chief, said in a separate statement, adding that all parties should “do their utmost to preserve the agreement.”

Iran challenges US

Iranian President Hassan Rouhani, at a cabinet meeting on Sunday shown on state television news, called the US move a sign of “certain failure” which only demonstrates that President Donald Trump’s strategy has resulted in “maximum isolation” for Washington.

On Saturday, the commander of the Islamic Revolutionary Guard Corps warned that Iran would set Washington’s military outposts in the Persian Gulf “on fire at once” if its adversary tried to start a war.

US to slap more sanctions

The US on Monday will sanction more than two dozen people and entities involved in Iran’s nuclear, missile and conventional arms programmes, a senior US official told Reuters, putting teeth behind UN sanctions that Washington argues have resumed.

Speaking on condition of anonymity, the official said Iran could have enough fissile material for a nuclear weapon by the end of the year and that Tehran has resumed long-range missile cooperation with nuclear-armed North Korea. He did not provide detailed evidence regarding either assertion.

A major part of the new US push is an executive order targeting those who buy or sell Iran conventional arms and will also be unveiled by the Trump administration on Monday, the official said.