Hackers reportedly targeted the computers of retired Admiral Mike Mullen, ex-chairman of the Joint Chiefs of Staff.
The hackers has breached Mr. Mullen's personal computers, which he used while working on the grounds of the U.S. Naval Academy since his retirement in 2011. The FBI is hunting for the hackers who responsible for the hack, The Wall Street Journal report says.
FBI agents took away two of Mullen's computers in October and returned them in November, according to the report.
One official said the evidence pointed to China as the origin of the hacking and that it appeared the hackers were able to access a personal email account.
Geng Shuang, the spokesman for the Chinese Embassy in Washington told the Journal he was not aware of the investigation and that his government prohibits cyber attacks.