If they're non-human in origin then the whole thing is even less actionable. We're not going to learn the secrets of hyper drive just because the military acknowledges that these are real phenomena.
I don't know. We would learn that some things are possible which we thought were impossible, which means physics took a wrong turn somewhere and we need to back up and keep looking. Even if it's not the secrets of hyper drive, that's probably going to lead to something interesting.
If they are real and non human maybe we can communicate with them and they can tell us. Highly unlikely based on their interest in our nukes and our obvious penchant for war