"While the use of WhatsApp, WeChat and as a messaging program is legal in China, we have seen in the latest espionage fee for a US citizen in Russia where the use of WhatsApp has been quoted in his espionage fees," read an email that seen by CNN.
Representatives of WeChat and WhatsApp did not immediately respond to a request for comment.
"Exercise Increased Caution"
"UC Davis Global Affairs routinely posts links to the State Travel Advisory and CDC (Centers for Disease Control) health care counseling for places where our faculty, staff and students travel," said spokeswoman CNN.
The email was sent by Gary Leonard, a managing director with UC's Risk Services Department, at the President's Office. Leonard, who travels, did not immediately respond to an email request for comment. Nor did a spokesman for the president's office answer.
The warning, which raised the threat from 1 to 2 on a four-point scale, urged Americans to "exercise greater caution in China because of arbitrary application of local laws and special restrictions for dual American Chinese."  "Don't sign anything"
China has always had a little worried relationship with foreign students.
The poster style showed a female named Xiao Li, who was showered with compliments, red roses, fine dinners and romantic walks in the park of David, a "visiting scholar examining questions about China" convincing her to share internal government actions.
Graduates and even some students who visit China have complained about being watched and followed by police or intervening to question their research and who they are talking to in the country.
In addition to warning "not signing anything," the new UC guidance instructs staff to be cautious with prolonged Q&A or interrogation to avoid inadvertently providing any information that may be distorted to deny resignation or facilitate an arrest. "
Previously, concerns have mainly focused on people's public statements or statements to the authorities, but the new management suggests that officials are concerned that even private comments may be used against graduates and students.
" New Level of Suppression "
UC's concern seems to be well-founded, China is increasingly breaking into previously tolerated areas of deviation, with even private comments being policed.
Twitter is blocked inside China and while a small number of Chinese dissidents and activists use the platform, their influence is limited and in the past they were most ignored by authorities na.
While tweets are public, the Chinese authorities have previously persecuted people for things that they say privately, especially on Tencent's messaging program WeChat, which has a record to conform to state censorship and surveillance.
"Many agencies have shown that Chinese authorities have access to private chat on WeChat," said HRW's Yaqiu Wang to CNN.
"The breakdown of Chinese Twitter users and the punishment directed at WeChat users for their private messages shows that the authorities have become increasingly intolerant of speech that is private or anonymous."
Experts have long warned to use WeChat for something sensitive, although Apple's pure dominance makes it difficult to avoid entirely in China.
"The reality is that ordinary Chinese often feel powerless and fatalistic about censorship and surveillance," she said.