Well, similar over 2000 years, but maybe not their 2000 years. Perhaps they are time travelers from our future and we see the same craft over time which it jumps around in, and avoiding contact because of the time paradox of changing the past. Or maybe they ARE changing their past to avoid what happened in our future, which given the subject of nuclear weapons, is rather dramatic. Who wouldn’t argue for killing Hitler before he came to power?
Well, that possibility is far too speculative for me, at this point.