Unlock the following missions by entering the corresponding case-sensitive codes at the "Bonus Codes" menu:

MISSION - CODE
Ambush (North American version) - AmbushU454
Ambush (European version) - SATURN
Attack From The Darkness (European version) - AMAZON.DE
Close Quarters - CloseQ8M3
Coastal Fortress (European version) - Play.com
Coastal Stronghold - StrongM577
Debris Field - OFPWEB2
Encampment - OFPWEB1
Fire Team Engagement - BLEEDINGBADLY
Night Raid - RaidT18Z