All depends on what is meant by the word which all-too-often denotes an all-inclusive label for a cluster of characteristics chosen according to the political inclination of the user.

Wikipedia says "Nationalism holds that each nation should govern itself, free from outside interference (self-determination), that a nation is a natural and ideal basis for a polity and that the nation is the only rightful source of political power (popular sovereignty)".

Which other particular source of political power would you suggest for the US or any other country ?