@nprofile1q... How can it being unethical to initiation force be problematic? That is all the NAP really is. It is a statement about what is ethical and a committment to being ethical. It is a standard in short hand form for what is right and wrong. We can't get to more ethical society by being unethical ourselves, can we?
Non-initiation of force doesn't mean we rule over to those that do initiate force. NAP is never against defending liberty. It is not against use of violence, only against initiation of force against those just going about their business. It says we can only ethically interfere with choice of others when they are initiating force to stop that wrong or when they are physically harming others.
What are borders? Are they not established by a State - by self legalizing monopoly initiation of force over everyone withing its claimed physical territory? That someone comes into that space without the State's permission says nothing about their intentions. If they live in ethical voluntary interaction with others why would I object? States have grand strategies and conspiracies of one against another. A bunch of free people voluntarily living and cooperating with one another? Not so much I suspect.
I think part that is hard is to learn to think outside the confines of reality as defined by the assumption that the State is legitimate and learning to recognize which problems are problems only with that assumption and perhaps not so much without that assumption sneaking in. It takes time and patience and then I often still get parts wrong or parts still aren't so clear.