Ghost Recon cheats and cheat codes for Playstation 2

All missions unlocked:
First press any buttons to stop the opening sequence.
Quickly enter the following button combination on the title screen:
X, L2, Triangle, R2, Select 
The start-up screen will change if the code is accepted.

All special features:
First press any buttons to stop the opening sequence.
Quickly enter the following button combination on the title screen:
L1, L2, R1, R2, X, Select 

Invincibile first soldier:
First press any buttons to stop the opening sequence.
Quickly enter the following button combination on the title screen:
L1, R2, L2, R1, Select 
Note: you can type also, when paused the game.

All guns
At the main menu, hit x, left, triangle, square, x, select.

Ghost Recon Desert Siege Bonus levels:
Finish the 15 normal levels

Medals: 
Purple Heart: Get wounded or killed in action.
Bronze Star: Get 15 kills
Silver Star: Get 20 kills
Distinguished Service Cross: Get 25 kills
Congressional Medal Of Honor: Get 30 kills 

Unlock all 12 heroes as playable characters in quick mission and campaign modes:
Finish the first 12 missions in campaign mode to