The alien invasion has already happened however the negative ET's that invaded work behind the scenes unseen. Thus "The Invisible Enemy" The Positive ET's can't come land until the majority of the population ask them to. The negative ET's through movies etc have implanted in our brains the idea of an alien invasion so we subconsciously think if aliens land they are probably invading.
The negative ET puppet world rulers would order their military's to attack the good ET's.
So then the negative ET's would laugh their asses off seeing the good ET's attacked and portrayed as invaders.
Then you have our free will which the good ET's cannot violate and the negative ones violate daily.
What a mess.