Explainer: U.S. says U.N. sanctions on Iran to be reimposed Saturday. What does that mean?

FILE PHOTO: U.S. President Donald Trump takes questions during a news conference in the Brady Press Briefing Room at the White House in Washington, U.S., September 18, 2020. REUTERS/Kevin Lamarque

NEW YORK (Reuters) - U.S. President Donald Trump's administration says that on Saturday (2000 EDT/0000 GMT Sunday) all United Nations sanctions on Iran have to be restored and a conventional arms embargo on the country will no longer expire in mid-October.

But 13 of the 15 U.N. Security Council members, including long-time U.S. allies, say Washington's move is void and diplomats say few countries are likely to reimpose the measures, which were lifted under a 2015 deal between world powers and Iran that aimed to stop Tehran developing nuclear weapons.