Call of Duty 4: Modern Warfare/No Fighting in the War Room

Objectives

 * Get to the launch control room
 * Plant the C4 on the wall to the launch control room
 * Upload the abort codes
 * Follow Captain Price

Get to the launch control room
Once you start the mission, follow Captain Price to the air ducts. After you get out, head through the changing rooms and when you reach the red corridor, go to the right. You will be told that you have 15 (Recruit) to 9 minutes (Veteran) to enter the abort codes so you will have to move quickly. There will be two enemies coming out from a kitchen area, kill them then wait and a third will come out. Kill them all then go through the doorway, pick up an AK-47 on the way as it will come in useful later. Look through the doorway to the right and pick off all the enemies, some more should come if you move into the area, kill them as well. Now slowly head down the next red corridor with sights up, picking out any enemies that you see. After you reach the end, there will be a large room with quite a few enemies in. Wait for your team then kill them all, maybe use a grenade or the grenade launcher if you are having trouble. Go down the stairs and reload all of your guns in the small break.

Follow Captain Price
You will have to go back the way you came from, when you reach where the large door is, look left and aim your gun at the door, you will find 3 enemies coming from a corridor, kill them then slowly look down that corridor, use the grenade launcher if you want, you're nearing the end of the level.

After you get past them go to the end of the corridor, into the lift. You will end up near the vehicle depot, follow your team then engage the enemies there. These are not really a threat, use up all your grenades and grenade launcher ammo if you want as this is the last fight. After all the enemies are dead, wait and the level will end.