[clearcarbon]

"THE BIG DECEPTION: "Unclassified then became classified later""

There's no point in marking or designating an unclassified document SECRET after everyone has already looked at it. That might just make it more desirable.

[CivilWarBrewing]

The sole purpose of a classification marking is to FLAG the reader as to HOW THEY SHOULD HANDLE WHAT THEY ARE READING. That's ALL it's for, nothing else. Protecting national security through proper handling is what a marking is for.

If the enemy reads something they've been itching to find out but haven't been able to due to proper handling of said information THEN THEY REALLY DON'T CARE IF IT'S MARKED OR NOT. The marking is for US, not for THEM.