In a grand palace build from smoldering meteorites on a distant planet, snail-like rulers of lizard-like creatures listen to their UFO pilots returning from recognizance missions to the Earth. The pilots are in agreement that it would take at least a century to transfer enough conventional weapons to Planet Earth to destroy it.
So the snail-like rulers have no choice but to order their raccoon-like scientists to devise a much more compact weapon: a super-light-weight powder with the same specific weight as the Earth atmosphere that paralyzes human-brain when released from special UFO sprayers.
The UFO pilots return back to Earth in the mid 1960s of the local calendar, but the powder doesn’t seem to be strong enough for the expanses of the Earth surface. In ten years it affects only a minority of the Earth inhabitants with just a wishy-washy paranoia about global warming.
Obviously, brain-paralysis virus cannot be spread in the Earth atmosphere indiscriminately just like that. So when the UFOs return to Earth again a few decades later, they become more selective, concentrating on spreading the brain virus exclusively in government buildings and media outlets.
And, lo and behold, it works. Merely a year later, the Earth is on a total lock down, with the Earthlings whining and moaning and peeing in their pants about an unidentified specter of deadly infection . . . all except for one country: Sweden, where the brain-paralysis powder happened to get blown away by icy Arctic winds.
So the snail-like rules of the distant galaxy have no choice but to send out their UFO fighters to wipe Sweden out with conventional explosives — except that the Swedes have their Superman, who takes off from the Royal Palace in Stockholm with a pat on the shoulder from the king himself to blow the invaders to smithereens.