OK, I'll play devil's advocate on this one. Yes. trespassing and shoplifting, pick pocketing, etc. basically, if I want it, I have the right to take it, is a problem in USA. BUT...for the first time, I am talking from the other side of the fence. Just because you have a no trespassing sign, doesn't mean you have open season on humans.

Case in point...we are inheriting an old house, the redug pond and a few acres to the east of the house. The house west side has a fence right next to it and back about 200 ft. with a small and large gate for access out the gates, up to the road in front of house and east to pond and fields with mower and tractor. The property was divided up by brothers(wife's granddad and brother many years ago. The brother put up a bob wire fence then, and it goes back and slants behind the house...obviously not on a N S line as sections of land were divided up then.
Well, fast forward to 30 yres ago, when my in-laws built the house and put up the fence on the west side back about 200 ft, then over to the east side. The son of the older guy that put up the original 'property line' fence always let my in laws plant a garden in the vacant 11 acre field to the west, and of course,access to the land for far enough to get the equipment in and out. It has always been a gray area. Everyone you talk to has a different description of the property line.
3 yrs. ago, a man bought the 11 acres with idea of building small houses on it. This was before we ever started staying there intermittenty. Now, being in the city on a postage stamp lot for 40 yrs, property line fights were as foreign as stories of Hatfield and McCoys.
Long story short...err.. too late for that; The guy has wondered over 3 times, 1st from his place to the back large gate, introduced himself and we started talking about some hunting trespassers he has seen on his game camera near the back of the property. He started talking about no trespassing signs and 'somebody might get hurt' etc. He is also a part time resident of the property. I told him I would be on the lookout for them. By the way, he had a Weatherby 7mm mag. strapped over his shoulder. Oh yea, his 1st spoken words were 'can I trespass to walk my property and look around?" after we started chatting, and forgot about the walkabout, I drove over to his house and invited him to come, that I had forgotten. He declined, saying he has a bad back and had done enough walking for the day.
2nd meeting, a few wks later, I was at the pond around the dam, which is toward the back of the property. I heard several high powered shots and birds scattering behind my dam. I thought it was the hunter trespassers; drove over to the area of shooting, and it was the land owner. I told him I was working at my pond, and it seemed the shots were pretty close and that I thought it was the hunters and came to investigate. He was shooting from his hood and out toward behind my dam and several hundred ft.back; he showed me it was at a downward angle. We both agreed that it was a little too close for my comfort.
3rd meeting, I had parked the UTV near the forward side gate and went inside briefly. He was on tractor and stopped. I re-introduced myself....idle chatter...then it became apparent that he was treatening me with putting up a sign, and somebody could get hurt, etc. I politely told him that I dont intimidate easily.
Then we started talking about the line always being vague, and the guy he bought it from(wife's uncle across the road) told him there would be property line trouble. I never knew any of this stuff had been going on. He says he had it surveyed; I asked to see the survey...because, I really dont know the property, he asked me if I wanted to get it surveyed; I said no, why should I, you can show me yours. He said he had a survey mark from the other corner, but never said he had a mark on the back of the property line.

Still dont know where the actual 2 points are, and I'll be damned if I am gonna be threatened over a line in the sand that I cant see or be shown. Note to all...know what the hell you are protecting before you start spouting off at the mouth. and dont treaten too harshly unless you intend to back it up.