H.S.A
The "Human Salvation Army" is a mercenary group that appeals to the (tree huggers) on Earth as the income of the faction(by fakly appealing to them as a nature loving organization) they are trying to find new places for mankind to live and prosper(since earth is a barren wasteland,except for the cities of course.) and once the leaders heard about pandora and the natives,they mobilized an extremely large military force(2 times the size of the RDA forces that were sent to pandora) and after the RDA forces fell,the H.S.A decided that while the natives( the Na'vi) were still regrouping(and recuperating) from the last attacks they would go in and finish the job,thus freeing up Pandora for terraforming and later populazation of humans.