China’s President Xi Jinping in Madrid on Nov. 28. (Juan Medina/Reuters)

AFTER A few decades of engagement and openness with the West, China under President Xi Jinping has shifted to a strategy of defending and promoting its authoritarian regime, including through an influence campaign inside the United States. It seeks to “penetrate and sway” the Chinese American community, Chinese students in the United States, U.S. civil society organizations, universities, think tanks, media and businesses. That is the conclusion of a new report by an impressive group of U.S. scholars, who warn that China’s political operations in the United States cannot be ignored.

The report, “Chinese Influence & American Interests: Promoting Constructive Vigilance,” written by a team led by Larry Diamond of the Hoover Institution and Stanford University and Orville Schell of the Asia Society, deliberately refrains from alarmism, and the authors make a determined effort not to stir hysteria that could rebound against Chinese Americans and lead to a new red scare. They point out that China has not sought to interfere in a national election or to sow confusion or inflame discourse in the ways that Russia has done.

But these experts, many of whom championed engagement with China in earlier years, portray a looming and malevolent force that is taking advantage of U.S. openness and freedoms to advance the goals of the Chinese Communist Party, which believes in neither. The fruits of this campaign, which has accelerated since Mr. Xi took power in 2012, are both greater sway in the United States and a cherry-picking of valuable technology. The report advances the idea that China’s earlier soft power has now been transformed into “sharp power” that can “challenge, and sometimes even undermine, core American freedoms, norms, and laws.”

What’s most striking about the report is the cumulative evidence of this quiet wave. While China’s theft of intellectual property by hacking is well known, the report describes how China has fielded a lesser-noticed, informal network of “collectors” who are “operating under the radar” through a maze of ventures to harvest U.S. technical know-how for China’s economic priorities, including semiconductors, robotics, information technologies, aviation, artificial intelligence and electric vehicles. This is no haphazard system, they report, but is run by a methodical apparatus devoted to collection, distributing stipends, sinecures and cash to those who help. China’s agents often get shopping lists of stuff needed back home.

This quiet, determined effort has at its core a vast, undeclared army of people who are doing China’s bidding by infiltrating open U.S. institutions to gain influence, steal secrets and exert leverage, the authors note, ruefully pointing out how the playing field is not level. China takes advantage of the open society in the United States but, at the same time, slams shut the doors inside China, making it almost impossible for scholars and journalists to carry out the same kind of activities in the police state that is the People’s Republic. To remedy this imbalance, they wisely suggest that the United States needs to expose Chinese influence campaigns, as well as enhance defenses against abuses. It is time for more clear-eyed understanding of what China is up to on these shores.