Imagine a world where each country has its own territorial disputes and their national boundaries have overlapping claims over others.
I suggest give those countries a reason to actually dispute a territorial claim.
In this mechanism, each country has the right to draw and organize what would be the actual line of control for each nation involved in that dispute.
If someone disagrees with that agreement, then they now have justification to declare war on that particular nation.
And also, maybe we can give players some power in deciding what should be their preferred territorial boundary of their country even if that area was part of another country they didnt even control yet.