Bosnia Herzegovina is a nation state built on fragile foundations. It emerged from a brutal ethnic war. Its make-up - a Serb mini-state reluctantly yoked to a Muslim Croat federation - is dysfunctional. And there are now fears it could disintegrate. Zeljka Cvijanovic is the Prime Minister of the Republika Srpska enclave in Bosnia. Are the separatist Bosnian Serbs playing with fire?