China, one of the world’s biggest oil importers, has ramped up its purchases of U.S. oil as a glut of American crude makes it cheaper than Mideast rivals, according to The Wall Street Journal.

Congress lifted a 40-year ban on U.S. oil exports two years ago as production rose to the highest in decades. China now buys 100,000 barrels a day from the U.S., 10 times the average of a year earlier. Imports in April and May jumped to more than 180,000 barrels a day on average, according to China customs data cited by the newspaper.

American producers welcome the new market to help pull them out of a three-year price slump that has hurt profits and jobs. While Russia, Saudi Arabia and Angola are still the top suppliers to China, U.S. oil sales may reach more than $1 billion this year, up from $150 million last year.

China has sought to diversify its suppliers as its oil fields become less productive and geopolitical worries threaten to disrupt supply from the Middle East, such as the decision by Saudi Arabia and other Arab nations to cut ties with Qatar last month.

“If there’s opportunity to buy [oil] from somewhere else, we should,” Lin Boqiang, an energy expert at Xiamen University who has advised Beijing on oil policy, told the WSJ. “The precondition is that it must be economical.”

Closer energy ties between the U.S. and China is seen as a bright spot in their relationship, which faces other challenges such as how to contend with a growing nuclear threat from North Korea. President Donald Trump also campaigned on a pledge to make trade deals with China more advantageous for American factories and workers.

China became the biggest buyer of U.S. crude oil in February, surpassing Canada, at a time when OPEC cut back output, according to Bloomberg News.

“The U.S. is a larger exporter of crude than many OPEC countries,” John Auers, executive vice president at energy consultant Turner Mason & Co. in Dallas, told the newswire. “That China is buying more means that the U.S. has become a larger player in the global crude export market.”

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