The character is a noble, or at least decent, soldier, who doesn't like the policies of their nation, but fight for it anyway. This person is loyal to their country, not its leader. Exactly how noble or decent someone can be while helping their nation do questionable deeds because it is "their duty" varies depending on the specific character and their actions. Moral Dissonance is something anyone can have and evil leaders are very good at exploiting patriotism. One does often wonder why someone so honorable fights for the evil side rather than deserting. At worst, this sort of thing can lead to the "I was just following orders" defense.