Treason
In law, treason is the crime of disloyalty to one's nation. A person who betrays the nation of their citizenship and/or reneges on an oath of loyalty and in some way willfully cooperates with an enemy, is considered to be a traitor. Oran's Dictionary of the Law (1983) defines treason as: "..."a"...citizen's actions to help a foreign government overthrow, make war against, or seriously injure the [parent nation]." In many nations, it is also often considered treason to attempt or conspire to overthrow the government, even if no foreign country is aided or involved by such an endeavour.
http://en.wikipedia.org/wiki/Treason