It would seem that NATO itself disagrees with you.
Edit: NATO are the imperialists. By any definition. Please read any of the following authors’s works on imperialism/empire: Hobson, Hilferding, Lenin, David Harvey, John Smith, Michael Hudson, Zac Cope, Anievas and Nisancioglu, Samir Amin, Giovanni Arrighi, Paul Kennedy, or Niall Ferguson.