If we're going to go down this tangent; why do we assume that any alien would be hostile to us? They could simply be explorers, as excited as we would be to find sentient life in the galaxy. Also, a species capable of interstellar travel would, one hopes, have evolved past the desire or need for conquest of lesser species (look at our own history as an example). Additionally, if they are that advanced, we are a trivial spec on the galactic map. Worth investigating, but not interfering with (think the
Prime Directive).
We can barely explore beyond our own gravity well. Only
one human spacecraft has gone beyond our solar system. Going all
War of the Worlds on little us would be like the US nuking an isolated Amazonian tribe. Why? Sure, that rare tree is worth some money... but we can get the same tree further up river and leave these guys alone.
No, I think that aliens exist, and I don't doubt that more advanced ones have peered upon us tiny humans for afar; maybe even going as far as to send an explorer here from time to time (explaining UFO's). But a vast government conspiracy to cover up contact or collusion? C'mon, these are the same bureaucrats that run the postal service, not buying it. And alien invasion, nah. If they really wanted to contact us, it'd be more along the lines of
Arrival or the Vulcans in
Star Trek : First Contact. Coming here due to curiosity and the desire to share knowledge.