Interesting thread subject but I disagree that the people in power would use a 'fake alien invasion' to try and control us in times of peril. Once you introduce a more powerful 3rd party (in this case the aliens) into the equation, the masses will stop listening to all previous forms of authority (political leaders, police, military, etc).

The easiest and safest way to exert control or influence over masses in times of peril would be to control or restrict their access to vital commodities like food & water.