In China’s cotton-growing Xinjiang region, farmers have been hailing a bumper harvest this autumn. But much of the crop is under U.S. sanctions, and where it will end up is a thorny question.

Xinjiang produces a whopping 85 percent of China’s cotton, which is made into garments sold around the world. Some of the largest Xinjiang suppliers have been banned since last year from selling to the United States because of human rights abuses in the region against members of the Muslim Uyghur ethnic minority.

U.S. and European policymakers are now discussing expanding the ban, with much of the world’s cotton products hanging in a regulatory and ethical gray zone. Enforcement is proving challenging, with fashion brands sourcing from hundreds of factories around the world with little proof of where the cotton originated.

Laura Murphy, professor of human rights and contemporary slavery at Sheffield Hallam University, says there is high likelihood that banned Xinjiang cotton is still making it to U.S. shelves, because it is shipped to third countries for clothing manufacturing.

“It obscures the provenance of the cotton,” she said. “Companies still have a long way to go to ensure they are not using Xinjiang cotton.”

In a report released Wednesday, Murphy’s team mapped out how cotton makes its way from Xinjiang fields to garments through an opaque web of suppliers. It says that more than half of China’s exported cotton go to countries in Asia — including Bangladesh, Vietnam, Indonesia and Cambodia — where it is made into clothing for further export to the rest of the world.

Asked about the possibility of fashion importers finding loopholes, Jeffrey Quiñones, a spokesman for U.S. Customs and Border Protection, said the agency continues to use all available resources to enforce sanctions. He said Xinjiang cotton-related cases accounted for the majority of CBP’s detentions for forced labor in the past fiscal year.

“Any person or organization can report detailed allegations of forced labor affecting goods bound for the United States by contacting CBP,” he said.

China’s government has repeatedly denied any forced labor took place in Xinjiang, although it acknowledges there were “vocational training programs” for residents that officials considered at risk for separatism or religious extremism. State television has shown local officials trying to persuade reluctant villagers in Xinjiang to agree to textile factory jobs.

“There is no forced labor in Xinjiang. Cotton-picking is highly paid work,” Chinese Embassy in Washington spokesman Liu Pengyu said in a statement on Tuesday. He called allegations of forced labor in Xinjiang “malicious lies concocted by a few anti-China forces.”

The Xinjiang regional government and China Cotton Association did not respond to requests for comment.

In 2020, the United States began imposing sanctions on several cotton suppliers from Xinjiang because of reports of forced labor, including the largest, a paramilitary organization called the Xinjiang Production and Construction Corps, which operates vast farms across the region.

Then in March, the Biden administration formally designated China’s policies in Xinjiang a “genocide,” citing the mass detentions of Uyghurs, and evidence of torture and forced sterilizations aimed at limiting the growth of the Uyghur population.

Around that time, Beijing organized a domestic boycott against H&M, Nike and other brands that had stopped using Xinjiang cotton to comply with U.S. sanctions. This forced fashion brands to pick between their businesses in the United States and China, the two countries with the largest consumer markets.

The effect was pronounced last week during China’s annual shopping holiday, a Black Friday-esque promotional day dubbed “Singles’ Day.” Chinese e-commerce platform Tmall reported that Singles’ Day sales of domestic sportswear brand Anta soared 61 percent from last year, surpassing sales of Nike and Adidas. Anta has patriotically pledged to continue using Xinjiang cotton, in contrast to Nike and Adidas, which said they halted sourcing from the region.

Beijing has been supporting Xinjiang cotton more directly, too, as overseas orders have fallen off. State-run China Agricultural Development Bank announced in September it will lend $7.8 billion to textile companies to help them purchase cotton this season.

For now, China is harvesting its first season of cotton under a new homegrown quality-verification process, after the region was dropped last year by the Better Cotton Initiative (BCI), which is used by major global brands like H&M to vet their suppliers.

While BCI has more than 2,100 members, the China Cotton Association said last month that so far 21 companies have signed onto the new domestic standard.

The restrictions on Xinjiang cotton may tighten in the West in coming months. In July, the Senate passed the Uyghur Forced Labor Prevention Act, with passage in the House of Representatives now needed for it to become law. The measure would broaden the U.S. import ban against goods made in whole or in part in Xinjiang.

In September, European Commission President Ursula von der Leyen announced the E.U. also plans to adopt a forced labor import ban, a measure largely interpreted to be aimed at the Xinjiang labor concerns.

Murphy said that many suppliers were using non-Chinese cotton to make products for U.S. brands to comply with Washington’s sanctions, while continuing to source for Xinjiang for the rest of their products. She said Western brands will need to consider if this arrangement meets the spirit, and not just the letter, of the sanctions.

“We have to think about, is that an ethical stance?” Murphy said.

Alicia Chen contributed to this report.