From Mark A.R. Kleiman's blog:
There's a story Khruschev used to tell, back when he was General Secretary of the CP-USSR (i.e., dictator). In the story, an Old Bolshevik goes crazy, and runs through the halls of the Kremlin shouting "Khruschev is a fool! Khruschev is a fool!" Naturally, he's promptly arrested, charged, tried, convicted and sentenced, to twenty-three years' corrective labor: three years for insulting the Party Secretary, and twenty for revealing a state secret.
An enormous amount of classified information consists of state secrets of the Khruschev-is-a-fool variety. And the incumbent adminisration is completely free to decide that revealing any given bit of information would be consistent with our foreign policy, and reveal it. As Henry Kissinger used to say, "I never leak. I de-classify." This is a huge problem, and an excellent reason not to have anything resembling an Official Secrets Act.
Excessive secrecy is a profound threat to national security, because secrecy helps cover up malfeasance, incompetence, and bureaucratic fumbling, e.g. with respect to the risk of terrorism at nuclear power plants.
Until the Democrats have candidates who can make that argument with a straight face, they’ll keep losing elections.