Ok alot of them have dogs tags but some of them dont. What do you do? Try them all! Run up behind them with the M9 and aim to fire. Raiden/Snake will say "Freeze". The enemy will put his hands up. Shoot beside their head and move in front of them and hold the gun to their head again from the front. They will start to shake. Most of them will drop dog tags.
Good bye everyone, it's been fun!
Special thanks to ED_, superman4u, and Cross Stinger
Credit for the Siggy goes to shadow slayer