He recently described Chinese schools as the “ideological front line” in a battle against concepts like rule of law, civil society and human rights. Any “wrong talk” in social science and philosophy forums, he said, must be silenced.

His colorful speech, which amplifies the talking points of internal documents that have been circulating over the past two years, appears so far to have had little concrete impact on the nation’s college campuses. Still, some academics expressed concern that such pronouncements would affect the quality of their teaching.

“Professors personally feel that they’re unable to properly explain things to their students,” said a faculty member at Yunnan University in China’s southwest, who asked not to be identified to avoid political repercussions. “They think, ‘Oh, these university students, it’s such a pity they won’t be able to learn anything good anymore. No wonder so many Chinese people are willing to go abroad to study.’ ”

Others warned that Mr. Yuan’s remarks were reminiscent of the ideological purification campaigns of the Cultural Revolution of 1966-76, the decade of chaos and violence unleashed by Mao that scarred a generation of Chinese intellectuals.

The notion that Western ideas are potentially subversive has been greeted with widespread incredulity, especially among Chinese intellectuals who note that Communism itself is a Western import. Xia Yeliang, a visiting fellow at the Cato Institute in Washington, said the campaign to vilify Western values was hypocritical.

“Was Karl Marx an Eastern person?” asked Mr. Xia, who was an economist at Peking University until 2013, when he was fired for what he says were his anti-establishment political views. “Weren’t Marxism and socialism adopted from the West?”

Both teachers and students, noting the growing surge of Chinese students studying abroad, say that China only stands to benefit from foreign ideas. In three years, the number of Chinese studying at American colleges soared 75 percent to more than 274,000 in the last academic year, making them the largest contingent of foreign students in the United States, according to the Institute of International Education. Among them was the president’s daughter, who attended Harvard University, arguably the world’s most renowned bastion of liberal Western learning.