There is no recognized public right to know any information that subverts the defense apparatus or benefits a foreign adversary. So even if you want to reveal a war crime you may need to wait until after it can't be proven in court to jeopardize national security. Until such time you would need to limit your disclosure to approved channels.

Anything else is treated differently. Stuff like waste, abuse, environmental issues, discrimination and the like are usually a different ballgame.