The Trump administration has imposed a ban on imports of cotton products manufactured by a Chinese state-controlled firm because of its reliance on the forced labor of detained ethnic minorities.

The Customs and Border Protection agency issued an order Wednesday ending shipments from the quasi-military Xinjiang Protection and Construction Corps. The order also requires any U.S. company seeking to import cotton products from China to prove they did not come from the XPCC or were included in the supply chain.

Xinjiang is a major source of cotton and textiles used by many of the world’s largest and best-known clothing brands. The XPCC produced as much as 30% of China’s cotton in 2015.

Ken Cuccinelli, the acting deputy secretary of the Homeland Security Department, which includes the CBP, said in a statement that any apparel attached with a “Made in China” label should be considered “a warning label” as it was made by “slave labor.”

Acting CBP head Mark Morgan said “China’s systemic abuse of forced labor in the Xinjiang region should disturb every American business and consumer. Forced labor is a human rights violation that hurts vulnerable workers and introduces unfair competition into global supply chains.”

The ban is in reaction to recent studies and news reports documenting how groups of people in Xinjiang, especially the largely Uighur Muslim and Kazakh minorities, have been recruited into programs that assign them to work in factories, cotton farms, textile mills and menial jobs in cities.