The U.S. is challenging Canada’s allocation of dairy tariff-rate quotas, saying they way it’s done undermines the ability of American dairy farmers sell a wide range of products to Canadian consumers.

U.S. Trade Representative Robert Lighthizer announced the enforcement action, which is being done in terms of the United States-Mexico-Canada Agreement, in an emailed statement Wednesday.

By setting aside and reserving a percentage of each dairy TRQ exclusively for processors, Canada’s “measures violate its commitments and harm U.S dairy farmers and producers,” Lighthizer said.

The move represents the first enforcement action under the new USMCA agreement, which went into force in July.