This is why there is poverty amidst plenty, why there is unemployment, insecurity and stress at the same time the means exist to secure every individual's well-being. Exploitation makes nationality irrelevant. Serbian capitalists and state bureaucrats exploit Serbian workers, while Croat owners exploit Croat workers. Each group of thieves wants the opportunity to exploit the other's workers even more intensely than it's own and uses its own nationalism against the other's nationalism as its excuse to do so. It only changes who does the exploiting.
Genuine freedom means ending exploitation.
Since workers of all nationalities are exploited, they have a common interest in uniting to resist and overthrow exploitation. The working-class outlook is international, not national. We must reject any nationalist appeal to kill each other for the benefit of our own nation's exploiters. Ours must be the genuine internationalism of worldwide working-class cooperation. The internationalism of the ex-Communists was a fraud, because they were themselves exploiters and are now desperately trying to remain so by adopting the murderous ideology of nationalism.