I don't know.
I know there would be lots of barking and a burglar probably would not enter.
I have a fenced yard and a dog door so mine have access to house and yard. I once had an exterminator come unexpectedly when I didn't have anyone to meet him. He said they were both fine. One hid in the doghouse and peeped out at him. (70lb bassador) The other ran behind the dog house but would try to sneak up on him and he would yell and she would run. (50lb blue heeler mix)
I also had my cousin cut my yard. He was going to be on a riding mower so I wasn't too concerned, but told him to watch out for the blue because she has been aggressive before with men and not to worry about the other one because he is scared of everything. He told me that the blue was fine, but the other one chased him around the yard while he was on the mower and tried to eat him up. I would have to see a video to actually believe that one. My bassador has never been aggressive with ANYTHING. The only time I have ever seen him protective was when I walked up and tried to pet a horse in a fence when I was walking him. He had never seen a horse or anything like it so he freaked out, barked, growled...his idea of protection was to bite my pants and pull me back while HIDING BEHIND ME.
I know my blue would attack if someone threatened me.