Documents like the NSAM and all the National Security Council records and resolutions really are WAY above Top Secret and may not be declassified for decades--if ever--so there really are subjects that one can go to jail for if they are leaked to the public.
And for a military person, there would be additional penalties such as changing the status of their discharge to dishonorable, and the loss of all pensions, pay and other benefits. With something like that on your record, even if they let you out of prison, you literally wouldn't be able to get a job at McDonald's. You would be unemployable, at least in the United States.
Edited by TheMacGuffin, 02 August 2012 - 07:10 PM.