President Trump’s administration should ban the export to China of technology that can be used for surveillance, a pair of Republican lawmakers urged Wednesday.

“U.S. companies should not be assisting in the expansion of China’s systems for surveillance, detection, and detention, or be complicit in what are gross violations of internationally recognized human rights occurring daily in the XUAR,” Florida Sen. Marco Rubio and New Jersey Rep. Chris Smith, the Republican co-chairs of a congressional panel dedicated to China, wrote to Commerce Secretary Wilbur Ross.

Chinese repression in the Xinjiang Uighur Autonomous Region has drawn international condemnation and the attention of Rubio and Smith’s Congressional-Executive Commission on China. The crackdown on internal dissidents plays into the Communist Party’s efforts to implement a critical infrastructure agenda through Central Asia, which also aids Chinese efforts to expand influence abroad.

“The U.S. government has clearly acknowledged the severity of the abuses in Xinjiang,” Rubio and Smith wrote. “Vice President Mike Pence and Secretary of State Mike Pompeo have both voiced public concern about these abuses and have specifically focused on the proliferation of ‘political reeducation’ centers or camps throughout the region. Our export policy must reflect this reality.”

They released that letter on the same day that Beijing warned Trump’s team not to impose any U.S. sanctions on Communist officials in Xinjiang. “China consistently opposes the US side using Xinjiang-related issues to interfere in China's domestic affairs,” Foreign Ministry spokesman Geng Shuang said during a press briefing.

Rubio and Smith led the call for those sanctions last month, after a senior U.S. diplomat described an historic crackdown on human rights in the region, which is populated by an ethnic Muslim minority.

“Beijing wagers that it now possesses the political, diplomatic, and technological capabilities to transform religion and ethnicity in Chinese society in a way that its predecessors never could, even during the peak horrors of the Cultural Revolution and other heinous Maoist campaigns intended to remake Chinese society,” Ambassador Kelley Currie, the second-ranked U.S. diplomat at the United Nations, told the lawmakers.

U.S. officials and analysts suspect that China’s perfection of the modern security state could have far-reaching implications in a global competition with the West.

“[Chinese] investments in artificial intelligence (AI) and facial-recognition technology appear to be giving Beijing the ability to monitor its entire population and make authoritarian rule efficient and effective,” Thomas Wright, a senior fellow at the Brookings Institution, wrote Wednesday in The Atlantic. “These technologies are highly exportable and will undoubtedly appeal to authoritarians or wannabe authoritarians the world over. These regimes will cooperate and share tactics and strategy, while working together to create a world that protects their interests.”

Geng denied any human rights abuses and warned the U.S. not to impose any sanctions. “In accordance with the law, the Chinese government protects its citizens' right to freedom of religious belief and people of all ethnic groups enjoy their full freedom of religious belief,” he said. “[W]e urge the US side to respect fact, discard prejudice and stop saying or doing anything that may undermine mutual trust and cooperation between the two sides.”