Reagan, SDI, and alien invaders
Is there any truth to the story I have read that one reason Reagan instituted SDI was to defend Earth against an alien attack?
Apparently he also thought an alien invasion would help to unite humanity in a common cause, though from what I see of human nature, that too would have been short-lived even if we did repel them.
All these hypothetical alien invaders would have had to do was drop a few big space rocks on us and SDI would have been worthless in that realm, too.