VDKMS

I'll give you my amswer MontyB.
You fight within the rule of law. I clarify.

In Antwerp (Belgium) there's a big muslim minority. Most local people don't like them. We could arm ourselfs but we don't, we stay within the rule of law. That's why there's a big right wing political party that gets many votes. The muslims came there legally (like the Jews in the region of Palestine). They bought property from the locals. (like the Jews in the region of Palestine). We didn't attack them like the Arab Palestinians did and still do. They cannot declare a state for themselves unless the Belgian government decides to give them one. The Jews couldn't declare a state for themselves unless the rulers decided to do so, and they did! For the Jews AND the Palestinians.
So, when you get a country from the UN and you get attacked by troops who rejected their country doesn't that give you the right to fight back?

Now about the "people who live there". Look at a timeline of maps here.
Who decided about the foundation and the borders of all those new countries? The people who lived there or the ones who ruled there? First come politics, then rule of law (created by the politics) then the people who live there. (in a democracy they choose the politics).