“All contracts are voluntary my friend, even big ones with fancy words and calligraphic penmanship.”
They are voluntarily entered into. That doesn’t make it excusable to voluntarily break them. If you breach a contract, break an agreement, go back on your word, you should expect those affected to extract a penalty from you if they can.
So, to prove your point you would demand war, death, destruction, disease, etc.. And at the end you would say, “You promised!” There are two types of law, contract and criminal. Criminal acts require action up to and including war. Contract violations require negotiation, penalties, and perhaps violence, but if you say it was necessary in all cases involving issues of political maps you are the epitomy of a warmonger. Self-determination is not scary unless your only goal is to maintain power.