China’s shopping spree of U.S. agriculture goods has extended to a rare purchase of soybean oil.

The Asian nation is the world’s top soybean importer and crusher. That’s why a sale of 20,000 metric tons of U.S. vegetable oil that was announced Thursday is a bit of an outlier. It’s the biggest such deal since November 2016.

Importers in China have ramped up purchases of American whole soybeans, corn, cotton and pork in recent weeks as China moved out of its coronavirus lockdown. It is now starting to fulfill pledges from back in January to buy billions of dollars more farm goods as part of the first phase of the U.S.-China trade deal.

“I’m not sure why they bought U.S. soyoil,” said Charlie Sernatinger, global head of grain futures at ED&F Man Capital Markets Inc. in an email. “Would seem to be strictly for Phase I numbers.”

Even if China’s soy crushers aren’t churning out enough vegetable oil, U.S. soybean oil is currently priced at a premium to Argentine oil, Sernatinger said. Soybean oil futures jumped by as much as 1.5% in Chicago.