On Monday, Senator Chuck Schumer, Democrat of New York and the minority leader, wrote in a twitter message that “the documents obtained by the @NYTimes show top officials in the Chinese Communist Party directed a brutal & repressive campaign against the Uighurs and religious minorities. While this should surprise no one, it exposes the Chinese Communist Party’s lies.”

The documents, provided by a member of the political establishment in China who is concerned about the crackdown, showed the direct involvement of senior officials in conceiving and ordering it. The papers included internal speeches by China’s leader, Xi Jinping, that laid the philosophical groundwork for the policy.

Mr. Geng, the foreign ministry spokesman, was asked about the article at a regularly scheduled briefing.

“It is precisely because of a series of preventive counterterrorism and de-extremism measures taken in a timely manner that Xinjiang, which had been deeply plagued by terrorism, has not had a violent terrorist incident for three years,” he said.

The Communist government once flatly dismissed reports on the mass detentions of as many as one million Muslims as fabrications, but since evidence of the camps has become irrefutable, it has stepped up attempts to defend its actions as justifiable steps to stamp out a national security threat.

Xinjiang has experienced violent attacks, but their extent remains unclear, in part because the authorities censored reports on them at the time and continues to restrict independent reporting.

After The Times published its report, China’s state media tried to rebuff criticism from ethnic Uighurs in the United States, whose criticism has been highlighted by Secretary of State Mike Pompeo. The Global Times, a newspaper owned by the Communist Party, reported that its own reporters had visited the relatives of those Mr. Pompeo cited and found them living happily in Xinjiang.