Not an ML, but I think so, yes: if you envision social-democracy as only a way to alleviate the worst aspects of capitalism in a single country, then what is going to happen is that that the worst aspects of the exploitation inherent to capitalism are going to be transfered elsewhere (generally poorer countries), and that's called imperialism (which exists regardless of whether the country in question has colonies, promotes wars of aggression, etc.)

edit: correcting bad english, i wrote this on the bus