[Legbreaker]

The CMTM was written with reference to the RPG as well as the movie, however it's very much from the viewpoint of the marines who've never encountered anything all that nasty besides other humans. Post "Aliens", provided the information got out, things might change somewhat.

Originally Posted by Raellus

I mean, if corporations ran the show, they would likely have their own militaries, right? Also, from the existence of the United Americas, one could extrapolate there are similar confederations for other regions. A new EU, an African Union, some East Asian union, SW Asia union, perhaps. I dunno. It's fun to think about.

In the RPG, yes, absolutely. The Corporations certainly do have their own armies, often filled with head hunted ex-colonial marines. Although they're more involved with security and corporate espionage, they do from time to time engage in "traditional" battles. The Corporate militaries are also much better equipped than the Colonial Marines.

The time of ALIENS is a chaotic one. Humanity is expanding into the stars and establishing new outposts and new colonies, but society is in danger of unravelling. The Nations of Earth have lost most of their power, and in their place the Corporations which led the way into space stand as the new rulers of Humanity. The transition of power from the Nations to the Corporations is an uneasy one, and confrontations are common.
Because of this, there is far more violence now than there was a generation ago. The Corporations used to be sensible enough to settle matters in court and take their legal losses with restraint. Now, issues which would normally go through the legal system cannot be allowed to drag on that long, especially if the case might end unfavourably. Everyone is more desperate than before, and Corporate and Mercenary forces are much more eager to cut out a piece of the future than ever before. Companies are changing hands so rapidly, with debts left unpaid and countless promises broken, that dozens of financial entities might hold title to a single piece of valuable property.
In the midst of the chaos, the Colonial Marine Corps stands as Humanity's peacekeeping force. It is the Corps which is charged with seeing that disputes are settled through law rather than violence, and which protects Colonists from unknown dangers and from sabotage by rival Corporations. Unfortunately, the Colonial Marine Corps depends on the Nations of Earth for financing and technology, and the Nations are no longer strong enough to support them. Because of this, the Colonial Marines are few in number and many places are beyond their reach. At the same time, Corporate military forces are more numerous and better equipped, and an increasing number of Colonial Marine commanders owe their real loyalty to Corporations rather than to the Corps. Faced with dangerous life forms, Human criminals, Corporate militaries, and internal corruption, the Colonial Marine Corps attempts to safeguard the future and well being of Humanity.
One good thing is that battles are now fought on a smaller scale than the wars of earlier centuries. The transportation of troops and equipment from world to world is expensive and time consuming, and the sophisticated military equipment being used means that the military profession belongs to an elite group of capable, highly trained people. Combined with the desire of the Corporations to avoid the destruction of factories and other economic resources, these facts have created military forces that use small numbers of well-equipped troops for clearly defined missions. For the Colonial Marine Corps, these Missions range from conflicts with Corporate forces to assaults on renegades and confrontations with new and dangerous life forms.

Because of the costs involved in sending troops across space, the Corporations prefer to have the Colonial marines do much of the heavy lifting whenever they can, much like occurred in the second movie.