All those who wish to fight against their "own" country are traitors, whatever the legal nicities. For me that includes any terrorist organisation (and their supporters) operating against free democratic government, anyone who was an "agent of influence" for the Soviets in the cold war, all those MPs who cross their fingers when taking the oath of allegeance and wives of Kings who commit adultory.
Call me a bluff old fashioned traditionalist but there is a lot to be said for hang-draw-and-quartering.