U.S. President Joe Biden on Thursday signed into law a bill banning goods from China’s Xinjiang region unless companies can prove they aren’t made with forced labor, in a move that will add to tensions over Beijing’s treatment of the nation’s Uyghur minority.

The bill passed with unanimous backing in both the House and Senate earlier this month, showcasing how Republicans and Democrats are largely aligned on China policy despite Washington’s deep partisan divisions on most major issues.

The measure is motivated by concern about the oppression of Uyghur Muslims in a region that holds a major place in global supply chains. Xinjiang is a source for cotton used in clothing and is a key location for producing polysilicon used in solar panels, which in turn are seen as crucial in the global shift away from fossil fuels.