The number of Chinese students in the United States has exploded over the last 15 years, as American colleges have tapped into China’s ascendant upper class as a major source of revenue. They are by far the largest contingent of international students, with more than 300,000 studying in the United States every year.

But despite a prevailing silence on political matters, they are not a monolithic group. Those who openly joined the protest last week include Sulaiman Gu, a Ph.D. candidate in chemistry at the University of Georgia who identifies as a dissident and a Hui, a Muslim ethnic minority. He is involved in a group called the Independent Federation of Chinese Students and Scholars.

Students at the University of California, San Diego, said that they had spotted posters earlier this week at the Price Center, a student center and food court. An English-language version was still up on Friday, but a Chinese version had been removed, according to Charlie Vest, a graduate student in Chinese economic and political affairs. In the past, pro-Beijing students in the United States have mounted counterprotests against students or speakers, like the Dalai Lama, who openly criticize or are seen as threats to the government.

How broadly the protests were spreading at each college was unclear. Shiwei Terry Zhou, a senior at U.C. San Diego from Wuhan, said that while some posters had been placed on the campus, he did not think the campaign was having much influence. “Most students are not anti-Xi as far as I know (they really just don’t care),” he said via a Facebook message.

Perry Link, a China scholar at the University of California, Riverside, said that such activism was more common immediately after the 1989 Tiananmen Square protests, after which Congress passed a law letting any Chinese student who feared retribution upon return to China to apply immediately for United States residency.