snapping labrador

My dog is just over 2 years old and has had a few episodes with strangers where he shows aggression by snapping at strangers. He has never shown any signs of aggression toward the people who he sees regularly but always seems nervous or on edge when stangers are around. My husband feels the dogs behavior is worse when I am around as if he is being protective of me. I think this could be part of it but also feel that he feels threatened himself by strangers. He will always go up to people and let them pet him but if they make sudden movements or bend over toward him to pet him he get defensive. His behavior is very deceiving in this way and I can usually ready him pretty well but strangers can not. He is not neutered so I question whether that is part of the problem, but I just want to know what I can do to make him more trustworthy around strangers. Any suggestions?

defiantely neuter him. that will help alot. he will be less aggressive when u do get him neutered. it might take awhile for him to tone done a little bit afterwards, but he will be more relaxed. And when he does growl or as soon as u see him be aggressive towards someone correct him right away.
   
good luck!