His time in Military Intelligence is ambiguous, it could be he transferred to MI to read and write information in Chinese or he may have actually went behind enemy lines. China was at war with japan at the time and a person that could read, write and speak Chinese would have been a military asset. His acting skills would have been an asset for him if he went behind enemy lines to gather intel.
He was a passenger on a plane that was hijacked, a bungling FBI agent shot several unarmed people some in the back. I have to wonder what happened to this agent career after this incident.