Again, you have to carefully consider before you decide to shore up an existing barb wire fence. Again, this varies state to state.
In SOME states, you can be liable if children get injured climbing on a barb wire fence. In some states, not barb wire, only razor wire would be an issue, or deliberately constructed dangerous traps in the case of adults. Legally, you have to remember that trespassing CHILDREN are treated very differently from adults. For example, a 'reasonable' person knows children tend to climb fences and ignore (or can't read) signs. The main tone of the law and liability in the case of children, is to protect the children from injury.
At the same time, remember that cases are treated individually. A person in a rural area isn't required to do outrageous things to protect neighbor children. He isn't required to replace his barb wire over 12,000 acres of grass land. Each case is different.
I lived somewhere once where the kids in the neighborhood burned down an old garage on my property. One day, I found them setting a fire in the garage I was using. I grabbed both of them by the coat, and started hop-walking them over to the corner of the property I thought they came from. On the way, I asked them where their parents lived. They told me. I hop-stepped them over to that house. I said to the parents that given that another building was destroyed on the property and that I had just seen them starting a fire in my garage, these boys were prime suspects for arson on the other building. I told them if the boys ever put even a whisker on the property again, I would get the DA to open investigation on the other building and they would go to juvie until they are 21, and they would not learn anyything very constructive or life affirming in juvie. I never saw the boys again. Sometimes all it takes is to be very clear.
I should add that we were fairly sure the boys did not burn the 1st garage down, but that the parents wouldn't have known that. It helps to have a card in your pocket that you can just very politely play sometimes. Just make sure it is a real good card, and you play it with a sweet smile.
I'm going to suggest that perhaps you could get away with putting up a non barb wire fence just in the area where children take their access to the property. I'm going to suggest the fence need not be 1000% unclimbable, and that it need not be as tall as Paul Bunyan. But you really should consult with an attorney to see what is 'reasonable' in THIS case. Many lawyers give a free or $25 or so first meeting.
People on the internet tend to have a very 'unreasonable' view of the law, that it is either totally unfair so ignore it(or at least get really mad about it instead of positioning yourself properly), or they read internet web sites with inaccurate information and get (and spread) wrong impressions that anyone can sue you for anything, or nobody can sue you for anything, which isn't true.
Certain dishonest lawyers WILL string people along and make money off of 'researching' their position when there is no likelihood they would even have a case let along win it, so when choosing a lawyer, it's best to ask friends in your locality, who best helped them handle a similar situation, and work off recommendations. But know this: today, lawyers specialize. My friend in rural Minnesota says he is called 'The Last General Lawyer'. There are very few Atticus Finches around today, who handle criminal law, debts, etc. If you go to a lawyer, pick one who handles property disputes regularly, and IN YOUR AREA. Don't just read their advertisement, ask them how many property disputes they've handlled of this type - RECENTLY.
Failing that, you can research your state and local laws and discuss with your county and state authorities what is best for you as far as fencing. Even the local district attorney might be willing to help you out, if approached politely.
A partial discussion of trespass involving children from lawbrain:
"These general rules have several exceptions, however. A property owner who knows that people frequently trespass at a particular place on his land must act affirmatively to keep them out or exercise care to prevent their injury. If the trespasser is a child, most states require an occupant of land to be more careful because a child cannot always be expected to understand and appreciate dangers. Therefore, if the property owner has a swimming pool, the law would classify this as an attractive nuisance that could be expected to cause harm to a child. The property owner must take reasonable precautions to prevent a trespassing child from harm. In this case the erection of a fence around the swimming pool would likely shield the property owner from liability if a child trespassed and drowned in the pool. "
There are several points made in the quote that aren't 'always completely true' or aren't the whole story or don't address how different states differ, so again, consulting with a (perhaps civil, real estate) attorney is the best idea.
You'll notice the home owner isn't required to take unreasonable steps to avoid liability. He isn't actually responsible for say, preventing a child from drowning in his pool by posting a child care person on his property 24/7 to deflect the children and herd them back to their property after they climb the fence. But he IS required to take REASONABLE steps to prevent it. Once he puts up a fence, he has fulfilled the 'reasonableness' part of the liability in most cases.
Civil law does take each situation case by case. If say, for example the fence was inadequate it might not protect someone from liability.
The thing to keep in mind, is that once you have a fence that defines your property line and protects YOU from the liability of a child getting hurt on your property, YOU are in a very good position to pressure your neighbors to control their children. In fact, you can calmly suggest that civil or legal action is a possible outcome of their trespass now that the fence is up, signs are up and your legal position is very publicly obvious.
Me? If it were a long and potentially costly fence, I'd try putting up signs that say no trespassing, and talk to the parents, and suggest that perhaps this problem could be resolved by them just keeping the children off your property. But I would be prepared to face the next step - building a fence.
Parents cannot always completely control their children. Children do tend to lie about where they're going and they love to find creeks, climb trees and get into mischief. Often it's the little one who's tagging along after 'the big kids' that are supposed to be 'watching him', that gets hurt. That one usually has no idea of any trespassing.
The problem is sometimes simpler when rural farming parents have children and teach them to respect fences and feel if they get hurt climbing a fence it's their own fault. But that is getting rarer and rarer today. With changes in parenting, many parents feel a child needs to be FREE and CREATIVE and that any restraint on him will DAMAGE him.
That is why I stressed before - DO NOT TALK TO, APPROACH, WARN OR OTHERWISE TRY TO DEAL WITH THIS THROUGH THE KIDS. TALK TO THE PARENTS. VERY NICELY, POLITELY.
Some people don't view property rights that way. And some people simply can't fully supervise their kids.
Of course, it would be NICE if it could be resolved where you and the parents get along so well you agree to let the children come in and play at certain times of day when mom or dad accompany them. It would be NICE if all that was required was a quiet, polite, non-threatening chat with the neighbors.
And as you can see from the tone people take on many of these threads about neighbor disputes, getting along, cooperating and keeping things down well below the flash point through quiet, polite negotiation - through being MORE cooperative and civil than 'the law' requires, most people, that is not their first priority. In fact, it's their last priority. Their first priority is to continue doing exactly as they want.
When the shoe is on the other foot - we want to keep chickens where they are not allowed, our dog is barking at night, we want to let our offspring run free, we don't always consider first, the goal of keeping the community peaceful and cooperating - we tend to blame others and find fault instead.
Perhaps if you look you can even find a thread here of a parent complaining that a neighbor won't let their dear children play on the 'tiny creek' that is just 'barely over the property line', that 'was a part of my grandpa's farm, which I have such fond memories of' and 'what is happening to rural America today', with many a chorus of 'hear hear!' and 'how unfair!'
Perhaps it's even by the parents of your little trespassers...LOL!!!