The so-called "Dulce Facility" in New Mexico and the reported human/alien stand-off could be a strange case of the telephone game mangling the truth as to a failed US Army assault on an installation built and operated by aliens given government land as part of a pact.
Or that the US Navy's Sidewinder missile project had a planning stages only offshoot known as the Diamondback: A nuclear warhead tipped air-to-air missile. The XCOM part? Why do you need that strong of a homing missile to fight another terrestrial plane, all the way back in the mid 50's?
Or the possibility that the Star-wars Defense System wasn't designed to aim toward earth but away from it.
Or that while governments and citizens may stay true to earth and not buy into pacts, that corporations and CEOs could be different. Some ancient power-players having had more hearts than a medical examiner weighs in a week, if you buy into the rumors...
And what about recent technology... There's that death-bed confession video from that Boyd Bushman. Whether a hoax or real, it's a definite reason to look twice at some of the stuff in your house.
Or, that several Russian space modules and satellites had guns. Like decently big ones, not something a cosmonaut holds.