The U.S. sanctioned a top member of China’s Communist Party on Thursday, along with three other senior officials and a Chinese entity involved in systematic human rights abuses of Muslim minorities and ethnic Kazakhs in China’s western province of Xinjiang. The action is likely to ratchet up already high tensions between the U.S. and China.

“The United States will not stand idly by as the CCP carries out human rights abuses targeting Uyghurs, ethnic Kazakhs, and members of other minority groups in Xinjiang,” Secretary of State Mike Pompeo said in a statement, referring to the Chinese Communist Party.

The Trump administration has likened China’s mass detention of more than 1 million Muslim Uighurs in Xinjiang to the worst human rights abuses since the 1930s, when 6 million European Jews were killed in the Holocaust.

Among those sanctioned were the architect of the detention camps, Chen Quanguo, the Communist Party secretary for Xinjiang. Chen developed the system of mass surveillance when he was party secretary of the Tibet autonomous region from 2011 to 2016. He later used the same tactics of “forced labor, arbitrary mass detention, and forced population control” over the Uighurs and other Muslim minority groups in Xinjiang, the State Department said in a press release.

Zhu Hailun, party secretary of the Xinjiang Political and Legal Committee, worked with Chen to establish the policies and procedures for managing the camps, including “abnormal deaths” and not allowing “escapes,” according to a Treasury Department statement.

It is the first time such sanctions have targeted sitting Chinese officials, and Chen, a Politburo member, is the highest-ranking Chinese official ever to have been sanctioned under the Global Magnitsky Act. The measures include travel restrictions on the four people and their families to the United States.

The sanctions are the latest in a series of actions the U.S. has taken against China since the start of the COVID-19 pandemic and the imposition of national security legislation restricting the autonomy of Hong Kong.

“The United States is committed to using the full breadth of its financial powers to hold human rights abusers accountable in Xinjiang and across the world,” Treasury Secretary Steven Mnuchin said in the announcement.

It is unclear what practical effect the sanctions will have on the officials, who would be unlikely to travel to the U.S. and whose financial assets are probably based largely in China.

Naomi Kikoler, director of the Simon­-Skjodt Center for the Prevention of Genocide at the U.S. Holocaust Memorial Museum, described the action as a “rare glimmer of hope.”

“The new sanctions are an important response to what constitutes crimes against humanity committed by the Chinese government. However, much more remains to be done,” Kikoler said. “The abuses in Xinjiang demand a coordinated response from the global community to halt crimes against humanity and provide accountability and security for the Uighur people.”

Trump signed legislation last month aimed at addressing human rights abuses of Uighurs in China, but he already had the authority to target the Chinese officials under the Global Magnitsky Act. Asked last month why he had yet to punish Chinese officials responsible for the camps, Trump told Axios, “Well, we were in the middle of a major trade deal.”

Former national security adviser John Bolton has said Trump told Chinese President Xi Jinping that he supported Beijing’s construction of “concentration camps” to detain the Muslim minority population.

“According to our interpreter, Trump said that Xi should go ahead with building the camps, which Trump thought was exactly the right thing to do,” Bolton wrote in his recently released book, “The Room Where it Happened.”

China denies abusing the Uighurs and other minority Muslim populations, and it has threatened retaliation for last month’s legislation.

“We again urge the U.S. side to immediately correct its mistakes and stop using this Xinjiang-related law to harm China’s interests and interfere in China’s internal affairs,” the Foreign Ministry said in a statement. “Otherwise, China will resolutely take countermeasures, and all the consequences arising therefrom must be fully borne by the United States.”