Growing up, you get the impression that the political lines on the map are monolithic realities. But, this isn't entirely true. Many countries are cobbled together out of regions with strong centrifugal tendencies.
One example is the movement for Catalonian autonomy in Spain. This is grown bolder now that E.U. membership have made the stakes involved in national boundaries less significant.
Other examples abound, of course. Chechnya wants out of Russia, and supporters are willing to kill to get what they want. Iraq is on the verge of disintegrating under its new constutition. The Kosovo region of Serbia is effectively autonomous. Bosnia is also a country in name only. Nigeria is in the early stages of a low level civil war between the Muslim North and the Christian/animist South. In Sudan a civil war on the same grounds in nearing its end. Canada has faced the succession repeatedly in the face of calls for autonomy or independence from Quebec. The United Kingdom has, under Tony Blair, undergone major decentralization in order to quell autonomy demands from Scotland, Wales and Northern Ireland. Sri Lanka, Cyprus and Indonesia all have faced civil wars or outright partition as a result of regional divisions. Thailand is in the early stages of a regional Muslim insurgency against the Buddhist controled government based in the North. And, Columbia has ceded de facto control of much of its terroritory to a rebel group.
The United States has historically stood firm against efforts for regional autonomy in independent countries and the principal of self-determination more generally. But, couldn't there be a more peaceful way to resolve disputes over national boundaries and autonomy other than civil war? Often civil wars errupt simply because there is no room for compromise and no peaceful alternative. Almost by definition "break away" territories are an electoral minority in the countries they wish to leave or gain autonomy from, and for whatever reason, majorities are almost never willing to relinquish control of these regions.