Level 1: Baptism of Fire

Have the Green Beret crawl behind one of the two walls. When the guard moves away, run up from behind and kill him, being sure not to run through his line-of sight. Make sure the two patrolling guards can't see the body. You can hide in the shadows of the wall on the other side of the guardhouse until they move away. Then climb it and kill the guard with your knife when the patrolling guards are moving south. Hide the body behind the house.

The driver can hide behind the truck after the patrol goes by, and kill them from behind with his machine gun. Then he and the Green Beret can wait by the dock. Have the Marine put on his scuba gear and swim around to the northern side of the island he starts on, up where the guard is patrolling. Position yourself along the shore; when the guard passes, pop up and kill him with the harpoon gun, preferably out of sight of the other two guards. Swim down by the boat and kill the stationary guard with your harpoon when he is looking away and the patrolling guard is walking southeast. When the guard comes to investigate, pop up and kill him with the harpoon and grab the boat. Swim straight across to where the two guards are. Kill the patrolling guard with your knife or harpoon as he's walking away. Then kill the stationary guard.

Swim over to where your other two commandos are waiting and bring them across in the boat. Land behind the house to the bottom left of the screen. Kill the guard in the machine gun nest with your knife and run back behind the house. Select all three commandos and have their pistols ready. Waste the guards when they appear around the corner with the pistols or with the Driver's machine gun. Have the Green Beret carry the barrels over to the relay station and blow it up by shooting one of the barrels from a distance.