The Balkans?! Where each country borders its own borders/territories of old.
I don't think the conflict would escalate, though.
The Balkans have been boiling for ~1400 years or so (more if you include Macedonia's claim on Alexander the Great's empire). Modern day (19th century) massacres of thousands of people originate on the Balkans, too... no idea how/when it might be over.
Europe's history is full of clashes between & within its states.
Do those that lie here know why did they die?
And did they believe when they answered the cause
Did they really believe that this war would end wars?
Well the sorrow, the suffering, the glory, the pain
The killing and dying, were all done in vain
For young Willie McBride, it all happened again
And again, and again, and again, and again