The crackdown is turning into a campaign of fear and damaging academic ties between China and the United States, U.S. academics say. And coming as it does in the midst of the standoff over an American spy plane, it is becoming another irritant in Sino-U.S. relations.
Although the crackdown on scholars is not directly related to the wrangling over the spy plane, it is apparently another example of the internal jockeying taking place behind the scenes among China's leaders. On issues from how China deals with the United States to how it evolves politically, more reform-minded leaders are at odds with conservative factions in the Communist Party.
China's leaders recognize the need to send students abroad to study, and they see benefits to educational exchanges with foreign universities. The U.S. Embassy in China issues more than 15,000 student visas a year to Chinese citizens.
But the crackdown is seen as a warning from hard-line forces in China that scholars should not dig too deeply into topics that they deem embarrassing. Exactly what those taboo subjects may be remains unclear.
"This is very threatening," said Gilbert Rozman, a sociology professor at Princeton University whose work has focused on East Asia and Russia. "It's damaging the climate of exchange. We don't know how we can carry on normal academic activity in this atmosphere."
Among the other detained scholars are:
Gao Zhan, a permanent U.S. resident and sociology researcher at American University, who was detained Feb. 11 and accused of spying for unnamed "overseas agencies."
Li Shaomin, a U.S. citizen for six years who earned his doctorate at Princeton and taught at the City University of Hong Kong. Li, whose father was a well-known Communist intellectual, was taken in by security police Feb. 25 on unspecified charges.
Xu Zerong, a scholar from Oxford University and a legal resident of Hong Kong. Xu disappeared in October and is being held by police for unknown reasons.
Tan Guangguang, a Chinese intellectual with permanent U.S. residency who has taught at U.S. universities and worked for a U.S. medical group in Beijing. He was detained in December.
Some academics suspect the crackdown could be related to the recent publication of the "Tiananmen Papers," a compilation of internal Communist Party documents that outlined closed-door debates over the 1989 military crackdown on student protesters.
The U.S. editors of the book said the people who leaked the documents were trying to promote political reform. But Chinese authorities, embarrassed by the impression the book created of dissension among core leaders, derided it as a fabrication.
"All of us are worried," said Robin Munro, a researcher at the University of London and former Hong Kong monitor for Human Rights Watch. "We're assuming that Chinese state security has gone into overdrive trying to find out who leaked the Tiananmen papers."
On Tuesday, nearly 400 academics from 14 countries signed a letter to Chinese President Jiang Zemin, urging him to release the detained scholars. Among them were more than 75 Chinese academics living in the United States and elsewhere.
Mickey Spiegel, a monitor for Human Rights Watch, said the Chinese scholars took a risk in coming forward. "They have the most to lose," Spiegel said. Like the detained scholars, they could be labeled as hostile to the government by Chinese authorities.
A year ago, when Song Yongyi, a librarian from Dickinson College in Carlisle, Pa., was detained by Chinese police for six months, only eight Chinese scholars were willing to publicly come to his defense.
This time, Song himself took the lead in recruiting Chinese academics to step forward.
"Through my ordeal, Chinese scholars learned a lot," Song said. "People recognize one thing: If you want to be protected by academic freedom, you first need to fight for other people's academic freedom."
One of the scholars to join him in protest was Zhou Zehao, a librarian and Internet research specialist at York College in York, Pa.
"It has to start somewhere with somebody," said Zhou, now a U.S. citizen. "I don't want to sound like I want to put my head in the guillotine, but I feel duty-bound."
On Thursday, the U.S. State Department issued a warning that Americans of Chinese origins could be detained in China for spying if they have written critically about the Beijing regime or had close contacts with Taiwan.
"This makes everyone who has been doing research in China stop and think about what the limits are," said Eric Thun, an assistant professor of politics and international relations at Princeton. "But the real problem is no one knows."
"No one is quite sure what forces are at work here or why they are targeting overseas Chinese," Thun said.
One possibility could be that Chinese scholars have access to information not available to their Western counterparts, he said, "and that's why they're clamping down a little, to send a message."
Jennifer Lin's e-mail address is email@example.com.