Alien Game Plan
After seeing the pile of dog poo that was the remake of "The Day the Earth Stood Still", I was thinking about what would happen if Earth's major powers had to interact with aliens and whether they have thought out how to act in such a scenario.
In countless B movies and tv shows, an alien species decides to come to Earth for a purpose that is as of yet unknown. The powers that be debate about the aliens intentions and whether humans should blow up any incoming spacecraft or aliens that are headed our way. Or as Independence day (a Smith in each stinker), after aliens start invading, humans fight back and win.
What any character on these shows fail to think about is that any civilization advanced enough to get here can almost certainly travel at some level that is at least a fraction of the speed of light which puts them WAY ahead of anything we can comprehend. The nearest star to our sun is Proxima Centauri which is 4.2 light years away from Earth.
The fastest humans have ever sent any object is (the Galileo probe) about 100,000 miles per hour. At that speed, it would end up in Proxima Centauri in about 20,000 years.
Considering there is no advanced life forms in Proxima Centauri, the distances would be much much MUCH further. So whatever alien life form that wanted to travel here would have to either travel faster or more efficiently than the speed of light (if its possible), travel close to the speed of light for possibly hundereds of years, or travel much slower than the speed of light and have enough technology, resources, and patience to make a trip that lasts millennia. Either way, such a species could do whatever it wanted to humans as its technology would seem like magic to us.
Thus, the best course to follow if aliens come to Earth, would be to assume (and hope) they're benevolent. You're dependent on their mercy.