WASHINGTON (AP) — The Trump administration on Monday told five nations, including allies Japan, South Korea and Turkey, that they will no longer be exempt from U.S. sanctions if they continue to import oil from Iran.

President Donald Trump has decided not to reissue the waivers when they expire in early May, White House press secretary Sarah Sanders said.

"The decision is intended to bring Iran's oil exports to zero, denying its principal source of revenue," Sanders said in a statement.

Secretary of State Mike Pompeo planned to provide details about the administration's decision not to renew sanctions waivers for the five countries when they expire on May 2. The other countries are China and India.

It was not immediately clear if any of the five would be given additional time to wind down their purchases or if they would be subject to U.S. sanctions on May 3 if they do not immediately halt imports of Iranian oil.

Sen. Ted Cruz, R-Texas, applauded the end of oil waivers for Iran.

"This decision will deprive the ayatollahs of billions of dollars that they would have spent undermining the security of the United States and our allies, building up Iran's nuclear and ballistic missile programs and financing global terrorism," he said.

The administration had granted eight oil sanctions waivers when it re-imposed sanctions on Iran after Trump pulled the U.S. out of the landmark 2015 nuclear deal. They were granted in part to give those countries more time to find alternate energy sources but also to prevent a shock to global oil markets from the sudden removal of Iranian crude.

U.S. officials now say they do not expect any significant reduction in the supply of oil given production increases by other countries, including the U.S. itself and Saudi Arabia.

Since November, three of the eight — Italy, Greece and Taiwan — have stopped importing oil from Iran. The other five, however, have not, and have lobbied for their waivers to be extended.

NATO ally Turkey has made perhaps the most public case for an extension, with senior officials telling their U.S. counterparts that Iranian oil is critical to meeting their country's energy needs. They have also made the case that as a neighbor of Iran, Turkey cannot be expected to completely close its economy to Iranian goods.