Aggressive????

Question
I have a black, male cocker.  He is 1 1/2 yrs old.
He is very protective over myself and my 6 yr old son, but when we are walking in the neighborhood, friends come over to pet him (children 4-6 yrs old) and as long as I am petting him with the children, he is OK.  But, if I stop petting him and the children continue, he begins to be aggressive with snapping.  Is this normal temperament?  Are these dogs aggressive.  If so, how can I change this behavior????

Answer
It is not normal behavior.  You need to fix it.  You can't have the dog snapping at your children's friends.  Unfortunately, I don't have a solution I have confidence in.  with him on leash, you could give him a snap of the leash and a ''Bad dog!'' in a quiet voice that sounds like you mean it.  You could try letting them give him treats, a little of his kibble is enough.