False flag

A false flag operation is an act committed with the intent of disguising the actual source of responsibility and pinning blame on another party. The term "false flag" originated in the 16th century as a strictly figurative expression for an intentional misrepresentation of someone's allegiance, and centuries later also came to be used literally for a ruse in naval warfare whereby a vessel flew the flag of a neutral or enemy country to hide its true identity. The naval tactic was initially used by pirates and privateers to deceive other ships into allowing them to move closer before attacking them. Showing a literal false flag was later deemed an acceptable practice during naval warfare according to international maritime laws, provided that a vessel displayed its true flag before commencing an attack.

The term today extends to include countries that organize attacks on themselves and make the attacks appear to be by enemy nations or terrorists, thus giving the nation that attacked itself a pretext for domestic repression or foreign military aggression (as well as to engender sympathy). Similarly deceptive activities carried out during peacetime by individuals or nongovernmental organizations have also been called false-flag operations, but are more commonly called "frameup", "stitch up", or "setup".