PARIS (BLOOMBERG) - The United States has no authority to demand a snap-back in sanctions against Iran after quitting the 2015 nuclear deal two years ago, the French Foreign Ministry said in a joint statement with Germany and Britain on Sunday (Sept 20).

"We have worked tirelessly to preserve the nuclear agreement and remain committed to do so," the three countries' foreign ministers said in the statement.

Since quitting the nuclear accord in May 2018, the Trump administration has intensified efforts to pressure the Islamic republic, ratcheting up sanctions.

But the US moves have united partners like Britain, France and Germany with Russia and China, who have sought to salvage the accord.

That has left the US isolated on the UN Security Council, with most nations saying America has no authority to demand the return of international sanctions since it's no longer a party to the agreement.

The US says that the broader Security Council resolution that enshrined the accord doesn't require it to still be in the agreement, and that all of the United Nations resolutions on Iran that were in place before the accord - from a ban on arm deals to restrictions on the Islamic republic's ballistic missile activity and its nuclear enrichment - should have gone back into effect on Saturday.

The US expects all UN member states to comply with their obligations to implement sanctions, Secretary of State Michael Pompeo said in a statement late Saturday.