The Trump administration said Monday it will fully enforce unilaterally imposed U.S. sanctions against Iran, ending a waiver program that allowed some nations to continue buying Iranian oil without suffering penalties from the U.S. Secretary of State Mike Pompeo announced the tightening of sanctions Monday, saying the move will benefit Saudi Arabia and other U.S. allies in the Gulf.

Secretary of State Mike Pompeo: “The United States has been in constant discussion with allies and partners to help them transition away from Iranian crude to other alternatives. And we have been working with major oil-producing countries to ensure the market has sufficient volume to minimize the impact on pricing. Both the Kingdom of Saudi Arabia and the United Arab Emirates have assured us they will ensure an appropriate supply for the markets.”

Chinese authorities immediately pushed back against the move to ratchet up sanctions, saying it jeopardizes talks with the U.S. aimed at ending President Trump’s trade war. China is Iran’s single biggest customer of oil, consuming about half of the 1 million barrels Iran exports daily. Iran’s economy has suffered heavily since the Trump administration backed out of the 2015 Iran nuclear deal, which gave Tehran sanctions relief in exchange for a promise not to build nuclear weapons.