A senior raking officer in Star Fleet Command he plays an active role in trying to save Earth during an assault by the probe in Star Trek The Voyage Home, but when there is an attempt to normalize relations with the Klingon Empire (in Star Trek The Undiscovered Country) and possibly admit them to the Federation, he becomes a renegade who tries to sabotage the process for the good of Earth and the Federation, which, he fears, would be compromised by the presence of the long hated Klingons in their ranks.