You are Matt Baker, an soldier of the american army, You are a part of the Fourteenth Team, With your teammates (all main characters) you have to complete a lot of missions... But in the war all wont survive... you lost some teammates... and find others!
Have fun guys!
For all of my missions
http://www.gtaforums.com/index.php?s=42be930af89588bf0548cc71393a5c9f&showtopic=441786
There is ARMY Fourteenth Team 3 but isnt complete, you can check their missions on the topic