Before Al Queda, the West's biggest fear was domestic white nationalist terrorists like Timothy McVeigh.
EDIT: It's very disturbing that so many people don't understand what the Nazi platform was all about. The supremacy of the "Aryan Race" was literally a platform of the Nazi party from the beginning. The subjugation of Jews was a part of the party platform from the beginning. The use of paramilitary squads to enforce ideological purity was a part of the party from the beginning. And it just got worse from there.