Pompeo said that it would be a costly mistake for countries and companies to violate US sanctions by continuing to import Iranian oil after Wednesday, when the six-month waivers expire for eight importers – China, India, Japan, South Korea, Turkey, Taiwan, Greece, and Italy.

China, India, and Turkey are currently Iran’s largest oil importers, with China and Turkey offering pushback on the US decision. However, the sanctions waivers were only designed to give the countries time to find alternative supplies.

Pompeo, speaking at an event by news outlet The Hill, said: “We have had lots of talks with China about this issue. I’m confident that the trade talks will continue and run their natural course.”

These comments came as US Treasury Secretary Steven Mnuchin flew to Beijing for the remaining two rounds of talks to finalize a trade deal between the two economic powerhouses.

Pompeo also noted that the US has worked hard to find alternative oil suppliers to boost the global oil market when Iran’s exports are cut to zero.

He said: “We are convinced we can make sure the markets are adequately supplied. We are continuing to work on that. Companies that choose to violate the sanctions … we will pursue and we will ensure they are held accountable for the violations they engage in.”

On Friday, an official from the Donald Trump administration said that the US was not considering offering a wind-down period for the eight importers of Iranian oil or giving a short-term waiver for China’s oil purchases.

US sanctions law does allow the Trump administration to give Iranian oil importers a wind-down period before getting to zero oil purchases, including a short-term waiver, which is different from the 180-day exemptions offered by the US in November.

However, the Trump administration considers that the eight importers should have used the six-month period to look for other suppliers. Indeed, Greece, Italy, and Taiwan have already cut their imports from Iran to zero, while Japan and South Korea slowed down their imports recently while waiting to hear the US decision.

The US reimposed sanctions on Iranian oil in November after Trump pulled out of a 2015 accord between Iran and six world powers to curb Tehran’s nuclear program last May.