Operational security, not disclosing or revealing sensitive information about operations, including administrative movements and deployment schedules that could be used by terrorists or enemy forces to target the units/personnel executing the operations. More often used by chain of command as an excuse to get you in trouble when you mention that you’re being deployed over Facebook, even though the whole world already knows.

The CO burnt me for violating OPSEC for saying that I’m being deployed “sometime in the near future” over Facebook, even though the DOD just announced a massive troop surge for Afghanistan that aims to put U.S. Marines all across the smallest villages of Southern Afghanistan starting in January, but I guess I’m the asshole.