@johnribbon - I suppose it depends on how you understand nationalism. Traditionally it was mostly about waging war against other nations, but it is true that the modern version more seems to be a longing towards an ethnically (and racially) uniform village.
@Katharsisdrill It's more irony than a contradiction. Nationalism has often said "I'm not against other groups, I just think each should stick to their own". In that sense nationalist groups can align to forward common interests.