The FBI Cybercrime Division has been investigating several instances in which the security of several unclassified US government Web sites has been compromised. The origin of several of these attacks seem to be Web sites and servers based in China.
It is unknown at this point whether these hacking attempts are state-sponsored. As China only recently began to open its borders to the World Wide Web, there is a lack of information regarding the history of potential hacker threats there.
Investigations are further hampered by the US's lack of jurisdiction in China. - - "You can't just jump on a plan and go to China and start questioning people," a government official said. Source