The conspiracy theory idea I've heard is that at some point there is an intention to fake an "alien attack" in order to extend governmental power, etc.
it would have to be a democratic country with these types of capabilities. US, is the obvious choice
Sun blockers? Mr burns style, but to fight global warming - giant kites that reflect light upwards and absorb from below?
Perhaps one nation whose navy is being harassed by UFOs is demonstrating that they, too, can play that game.