That’s what happens when you have lots of trees on or adjacent to your property.

If that bothers you, don’t buy property adjacent to 200ft tall trees. They will fall. That’s what trees do. They grow, then die and fall over.

So move your fence 50 feet away from the property line. Obviously, this means you need to find a big property if it's adjacent to state land with large trees.

At that point he may be able to sue the state to fix it (or have insurance do it).

And if it’s your fence you can build one of the ones that’s cheap and easy to replace. I wouldn’t be shocked if you could put chain link back up after some straightening. You could use the downed tree to fix the fence if it was split log (not so good at keeping dogs in though)

I assume this kind of property is large enough that OP can afford to build the second fence one tree height away from the property line.