Successfuly complete the game on "Ensign" Difficulty setting and you will unlock terrorist weapons located in the armory while in single player mode.
Successfuly complete the game under the Lieutenant Commander difficulty setting
Plant a C4 on the outside of an outhouse and one of your men will say " I guess I will have to hold it, right Sir?
Run up to a door while holding X and release X when you get near the door to kick the door open.
Successfuly complete the game on "Rear Admiral" difficulty
To deffuse a bomb, point crosshairs at the bomb, and say "Bravo, diffuse bomb".
To order team to go into stealth mode, say "Team, low profile".
To subdue and enemy, sneak up behind the enemy and say "Hands up, get down".
Enable your team to have sniper rifles, when doing this, your team will shoot all of the snipers that are not visible by you, which makes the levels much easier.