The Trump administration’s plan to stop waiving sanctions for countries that import Iranian oil could further upset an already volatile international trade climate and, possibly, sour U.S. trade talks with China, which relies heavily on oil from Iran.

The temporary oil waivers, known as Significant Reduction Exceptions, will not be reissued after they expire on May 2 as part of a U.S. effort to tighten the screws on Iran, cutting the country off from its main revenue source.