The first anyone knew of the Alien presence on Earth was when a large underwater explosion destroyed the entirety of the island of Fiji.
The Aliens were quick to send a delegation—one of them an ambassador, they said—to Sydney. Their ambassador was, in turn, quick to express embarrassment and regret. The explosion was, he claimed, due to internal conflict between two of the, well—he hemmed and hawwed a little—two of the observation units currently sitting beneath our oceans. Observing, he emphasised.
Fiji was suddenly no longer the most pressing issue on people's minds.
The first thing to be done was to blame someone. The first round of blame was easily apportioned; it was obviously the fault of the Fijians. This theory had the significant advantage that the Fijians at fault were no longer around to argue. The Alien ambassador, unfortunately, felt it his reluctant duty to confess the presence of ‘observation units’ in every major ocean of the planet, and a few besides. (For instance, he explained, there were also units in the Mediterranean and Caribbean seas.)
So, for the second round of blame-casting, it was necessary to look a little further. The Admirals of the world's various navies were considered by their various governments to be a suitable target, for obvious if unjust reasons, and so the Admirals were rapidly—and with little dignity—retired. The people of the world relaxed, fault having been correctly assigned, and those in government relaxed, having once more escaped public inquiry with their positions and privileges intact.
This occupied so much of humanity's time that it was close to two weeks before anyone gave any serious thought to the Alien craft yet unexploded, still sitting in our oceans. The realisation that they had almost forgotten the Aliens completely was enough to set the people of earth off on another wave of hysteria.
The Alien delegation (and, indeed, the still-submerged Aliens) were nothing but impeccably behaved throughout this entire fiasco. Of course, it was sometimes hard to tell; it's difficult to project an aura of calm and dignity when your mode of conversation is to warble while waving your nose tentacles wildly about.
Still, eventually the right kind of minds prevailed, and an uneasy but stable understanding was reached. The Alien delegation was treated with the respect due any group backed by a large, technologically superior underwater army, but were asked to remain, ‘for their own safety,’ within a complex commandeered and adapted for their comfortable habitation.
Specially chosen negotiators were sent to talk to the Aliens, to find out why the Aliens were here, and hopefully discover their intent.
The Aliens were quite forthcoming; they had been, they said, simply observing, until they felt we were ready and mature enough as a race to be Contacted, at which point we would be asked to join the Galactic Community. It was all quite straightforward, and utterly benevolent, humanity was assured. The Fijian catastrophe was just a horrible mistake.
Humanity as a whole was too relieved (and excited) by this news to question it too closely. They began to put huge effort into the kind of things they thought the Aliens would consider mature—environmental policy became of prime importance, eliminating poverty and disease, global disarmament. Within months, spurred on by the thought of galactic acceptance, Earth had transformed itself into a fair approximation of a utopia. It wasn't perfect, of course, but all those big issues that had never been seriously dealt with were suddenly sorted, fixed, cured. It was a golden age.
Two-and-a-bit years after the Fijian catastrophe, the Alien delegation vanished from their conference room. There was a ‘blip,’ and suddenly the humans who had been meeting with them were looking at nothing but thin air.
Judging by the turbulence in certain parts of the world's oceans, it wasn't just the delegation that had disappeared. The return of sonar responses to previously dead patches of ocean floor tended to add weight to this theory.
There was only time for a few hours of anxious questioning and distress, thankfully. A large—Australian-sized—ship appeared in the upper atmosphere, and broadcast a message simultaneously over every television channel in the world.
The message was a simple one, in big, bold letters that scrolled up the screen. It read “THANK YOU SO MUCH FOR LOOKING AFTER OUR CHILDREN. WE HAD NO IDEA WHERE THEY'D GOT TO. YOU KNOW WHAT KIDS ARE LIKE, ALWAYS RUNNING OFF LIKE THEY DO AND PLAYING THEIR LITTLE GAMES. WE HOPE THEY WEREN'T TOO MUCH TROUBLE.”
With that, the ship disappeared in much the same way as the so-called delegation had, but with a somewhat larger ‘blip.’
The spectre of galactic oversight now gone, North Korea took advantage of the ensuing confusion to launch a nuclear attack on as much of the world as it had missiles for.