system
Given the following post, respond as if you're commenting on Reddit:
human
[XCOM Enemy Unknown] Why is the full force of the world's military not put to use when aliens invade?

In Enemy Unknown there are some points where aliens terrorize or show up in battle-class space ships and the media is clearly broadcasting that  we are not alone. Since the secret is out, why don't they make it a priority to integrate XCOM into a world/UN defense force? Is the information somehow censored?
gpt
Security. XCOM has known about the threat of alien infiltration for some time, and has been vigilant against it. Because of secrecy, world governments have not been protecting themselves against attackers with the goals & capabilities that the aliens have displayed. We know the infiltrators have made headway with some of these organizations, because we deal with corrupt politicians and even whole governments who pull out of the project. Furthermore, governments and militaries are much larger organizations than XCOM, and that means more opportunities for infiltrators to find an entrance.

XCOM is the last and best line of defense, and if they fall, so does Earth. While expanding their capabilities is a priority, the risk of exposing XCOM internals to potentially compromised organizations is high, and that is simply a gamble that cannot be afforded. 

XCOM has always planned on having to fight this fight alone. It has already made progress without the help of allies, and gives every indication of continuing to be able to do so. This is the path that we shall stay on. Vigilo. Confido.