The United States is ending sanction waivers to all countries importing Iranian crude or condensate seeking to drive oil exports to zero.
The White House confirmed the reports ahead of a press conference with Secretary of State Mike Pompeo set for Monday.
The current sanctions waiver given to eight countries including South Korea, is set to expire on May 2nd and any country still importing oil from Iran after that period are to be subject to U.S. sanctions.
The sanctions follow Washington's withdrawal from the 2015 Iran nuclear deal last May.
The reason to pull out of the agreement was that it "did not stop Tehran from developing its ballistic missile program."