The following special forces units are unlocked at the 'Main' menu by selecting the 'Community & Extras' option and highlighting the 'VIP' selection and pressing the Y button, then entering one of the following codes (without the quotes).
Unlock Russian Spetsnaz Guard Brigade
Enter the code 'SPZA39'.
Unlock Special Spetsnaz Battalion
Enter the code 'SPZT17'.
Unlock European Enforcer Corps
Enter the code 'EUCA20'.
Unlock U.S. Joint Strike Force
Enter the code 'JSFA35'.
Added by: Sanzano Nov 11th 2008, ID#2499