The Trump administration said Monday that it will no longer exempt any countries from U.S. sanctions if they continue to buy Iranian oil, stepping up pressure on Iran in a move that primarily affects the five remaining major importers: China and India, and U.S. treaty allies Japan, South Korea and Turkey. President Donald Trump made the decision as part of the administration's "maximum pressure" campaign on Iran that aims to eliminate all of its revenue from oil exports that the U.S. says funds destabilizing activity throughout the Middle East and beyond.

"This decision is intended to bring Iran's oil exports to zero, denying the regime its principal source of revenue," the White House said in a statement.

Announcing the step, Secretary of State Mike Pompeo said no more sanctions waivers would be granted when the current batch expire on May 2, choking off Iranian income that had been more than $50 billion a year.

"The goal remains simply: To deprive the outlaw regime of the funds that it has used to destabilize the Middle East for decades and incentivize Iran to behave like a normal country," Pompeo told reporters at the State Department.

The administration had granted eight waivers when it re-imposed sanctions on Iran in November after Trump pulled the U.S. out of the landmark 2015 nuclear deal. The waivers were issued 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. Three of those waivers, for Greece, Italy and Taiwan, are no longer needed because they have all halted their imports of Iranian oil.

But the other five continue to import Iranian oil and had 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.

China, one of Iran's largest customers, slammed the step, calling it more evidence of U.S. "unilateral sanctions and long-arm jurisdiction." China, which relies on imports for about half of its oil, could present the toughest diplomatic challenge for the U.S. in trying to enforce its sanctions.

Those arguments fell on deaf ears within the administration.

"We will no longer grant any exemptions," Pompeo said. "We are going to zero, we're going to zero across the board." Left unclear, however, is whether the five countries will face immediate American sanctions if they continue to take delivery of Iranian oil after the waivers expire.

Two senior U.S. officials – Special Representative for Iran Brian Hook and Assistant Secretary of State for Energy Resources – refused to comment on whether any of them would be given additional time to complete purchases made prior to May 2 or allowed to use money already set aside for purchases after that date without penalty. Both said questions about such provisions were "hypothetical," suggesting that some accommodation may be possible.

Fannon said the U.S. did not expect any sharp spike in oil prices or any significant reduction in the global supply of oil, given production increases by other countries, including the U.S. itself, Saudi Arabia and the United Arab Emirates. Those comments were echoed by Kevin Hassett, chairman of the Council of Economic Advisers, although benchmark U.S. crude oil rose 2.4 percent earlier yesterday after the decision was announced.

Hassett told reporters at the White House he's not concerned that the decision will negatively affect oil prices. He said U.S. production has risen in recent years by "more than all of Iranian production" so there is adequate capacity should there be a need for oil supplies. He said the link between oil prices and the U.S. economy has diminished as American oil production has increased.

"If the oil price goes up or down $10 a barrel now it doesn't have that much of an effect ... because our output has increased so much," Hassett said.

Iran hawks on Capitol Hill like Sen. Ted Cruz, R-Texas, who had long lobbied for the step, applauded the end of oil waivers.

"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.

Israel's Prime Minister Benjamin Netanyahu, meanwhile, praised the administration for further tightening sanctions enforcement on Iran, which the Jewish state regards as an existential threat. He said the move "is of great importance for increasing pressure on the Iranian terrorist regime."

Saudi Arabia says ready to ensure adequate oil supply

President Donald Trump said Monday that Saudi Arabia and other Organization of the Petroleum Exporting Countries (OPEC) nations could "more than make up" for any drop in Iranian oil supplies to global markets now that his administration has decided to end waivers that allowed some nations to buy Iranian oil without facing U.S. sanctions. "Saudi Arabia and others in OPEC will more than make up the Oil Flow difference in our now Full Sanctions on Iranian Oil," Trump said on Twitter. Saudi Arabia said yesterday it would coordinate with other oil producers to ensure an adequate crude supply and a balanced market after the United States said it would end waivers granted to buyers of Iranian oil.

"Saudi Arabia is closely monitoring the oil market developments following the recent statement from the U.S. government regarding oil export sanctions on Iran," Energy Minister Khalid a-Falih said in a statement.

"Saudi Arabia will coordinate with fellow oil producers to ensure adequate supplies are available to consumers while ensuring the global oil market does not go out of balance."