False flag

Something disguised to seem affiliated with a group OTHER THAN the one it really is affiliated with. For example, a "false flag operation" is a terrorist act committed by one group for the express purpose of discrediting another group, which is framed for it. False flag operations in warfare are usually conducted at sea. They are generally speaking illegal, although there are loopholes. The object is to disguise one's own vessel as friendly to the enemy until it is possible to engage said enemy.