The FBI is hunting for foreign hackers who targeted retired Adm. Mike Mullen's personal computers, according to a report.
Mullen, the former chairman of the Joint Chiefs of Staff, was targeted on computers he used while working at the U.S. Naval Academy after his retirement, The Wall Street Journal reported.
FBI agents confiscated two of Mullen's computers in October and returned them in November, according to the report.
According to Mullen's aides, however, he did not save or view classified information on his personal computers, the Journal reported.
Earlier this week, Switzerland's intelligence service warned the U.S. and Britain that secret counter-terrorism information may have been compromised in a security breach.