News of Mr. Yang’s reversion to Chinese citizenship reverberated across the Chinese-American community, especially among scientists and engineers. The C.C.P. gained much-needed respectability, having just poached a major human-capital asset of the United States, and one who had received most of his training there.

In fact, ever since the California Institute of Technology aerodynamics and missile expert Tsien Hsue-shen returned to China in 1955 — and became instrumental in building China’s missile industry — the F.B.I. has been well aware of the danger this peculiar kind of reverse brain drain poses for the United States. “I’d rather see him shot than let him go,” Dan A. Kimball, the secretary of the Navy in 1951-53, reportedly once said of Mr. Tsien. “He’s worth three to five divisions anyplace.” Hundreds of Chinese scientists overseas went back to China in the 1950s.

Mr. Yang’s renunciation of his American citizenship may have had an even greater effect, if only because there are many more Chinese-Americans in the United States today than there were some six decades ago. Certainly, his return to China in the 1970s was a great source of patriotic inspiration among my generation of Chinese studying and working in high-tech in the United States then. Again and again, such homecoming stories have helped repair the C.C.P.’s tarnished image after it lost the support of intellectuals — with its disastrous Anti-Rightist Campaign of 1957, the Cultural Revolution of 1966-76 or again after the brutal Tiananmen crackdown in 1989.

Longtime China observers readily recognize in Mr. Yang’s trajectory the handiwork of the C.C.P., specifically the painstaking orchestrations of its well-masked machine of influence. Foreign academic and intelligence circles, however, are only just beginning to appreciate China’s method — and how it differs from, say, Russia’s — and to take the full measure of its effectiveness. China’s ploys are difficult to discern, and its plants are difficult to dislodge, especially when they take root in unsuspecting open societies, like the United States, New Zealand or Australia.

The Chinese influence machine has nebulous outer layers, partly because connections between its members, be they individuals or organizations, are often imperceptible. But at its core is a well-defined, battle-tested structure first deployed by Mao in the 1930s. Mao famously identified it as one of his Three Magic Weapons against the Republican government of Chiang Kai-shek, alongside a Leninist party and the Red Army, and he gave it a respectable name: the United Front. The organization assumed its current form in 1946. Three years later, Mao’s Communists won the civil war, and credited the United Front in part for their victory.

The United Front comprises two organs, which are often poorly understood outside China because there are no equivalents for them in the West. One is the enigmatic United Front Work Department; the other is the high-profile Chinese People’s Political Consultative Conference (C.P.P.C.C.).