Near the beginning of the mission after surviving the Russian assault and retreating, you will be in control of 5 soldiers after a cutscene and youll have an objective to go to the village. Upon reaching an old man will agree to guide you for a favor. On the bottom right of the screen you will have 2 choices either to help him or not. Make a save and select intimidate. You can than reload and select the option to help. Achievement pops as soon as you press it.