According to Global Times editor, Hu Xijin
The tweet reads:
"Based on information I received, China will issue a warning on the risk of studying in the US. This warning is a response to recent series of discriminatory measures the US took against Chinese students and can also be seen as a response to the US-initiated trade war."
There's been plenty of talk about these responses and retaliatory measures from the Chinese camp but as of yet there's no official communication, so tread lightly for now. But there's no doubt that the message they're trying to send is that they're willing to pursue such course of action if the US does push things too far.