I have come upon this pretty fair video describing the outer visible layers of the breakup of Yugoslavia today, so I wanted to share some info and a few thoughts for better understanding of this topic.
https://www.youtube.com/watch?v=oiSgAiM0d8A
The question to begin with is why the country was formed on the first place.
In short, after the Medieval period, the South Slavic peoples in the Balkans found themselves being occupied either by the Ottoman Turkish Empire on the east or the Habsburg Empire on the west. During the national romanticism of the 19th century, an idea of liberation from both Ottoman Turks and Habsburgs, and unification of the South Slavic peoples emerged, although it was not the common thinking of all. The name "Yugoslavia" itself came from a Free Masonic lodge with the same name ("Yugo" meaning "South" and "Slavia" meaning "Slavic Land"), so Yugoslavia was basically a Free Masonic project. Its goals were basically these: to form an independant and unified South Slavic state, which would oppose the four main powers in the region: Turkey on the south, Russia on the east, Germany on the north, and Vatican on the west.
This idea was brought to diplomatic table during the WWI, and no wonder it was opposed by all the above mentioned four powers. Turkey was a power in decline losing territories, so it was of no actual importance anymore. Russia wanted to create a Great Serbia as a strong Orthodox Christian state, in order to spread its diplomatic and military and religious influence in the Balkans and therefore create a gate to the Mediterranean sea, and Russia also wanted to preserve the existence of the Habsburg Empire as a conservative force and future ally in the region. Germany wanted to connect to the Middle East and the Mediterranean sea too, and the unification of the South Slavs was preventing it in that goal. And Vatican wanted to spread its Catholic religious influence in the Balkans and to the east over the Catholic Croatians, so it saw the unified South Slavic state as an obstacle, too.
The modern Serbian state, since its final liberation from the Ottoman Turks begun in 1804, was developing itself under the strong influence of the American Revolution and the French Revolution and the Free Masonic classical liberal ideals, and therefore it has been seen by the surrounding conservative empires - Muslim Ottoman Turkey, Orthodox Christian Russia, and Catholic Habsburg Austria - as a hostile revolutionary element in the region. Most of the Serbian Free Masons saw the idea of unification of the South Slavic peoples as a chance to fulfil their Free Masonic ideal of brothers of different ethnic and religious backgrounds living together united in peace and prosperity. On the other side, Croatians wanted to liberate themselves from the Habsburg Empire, and they saw Yugoslavia just as a step forward to their full independance.
There was also a strong opposition to this idea among the Serbian people, with many claiming that a peaceful life of Serbs and Croats in one state would be impossible to achieve. However, the idea was brought to life in 1918, when the Kingdom of Serbs Croats and Slovenes was finally created, as a parliamentary monarchy under the Serbian royal dynasty of Karađorđević. The country was renamed to Kingdom of Yugoslavia in 1929. The idea was to create a new Yugoslav nation, similar to the American nation, which would consist of different founding peoples - Serbs, Croats, and Slovenes - and of different religions - Orthodox Christian, Catholic, and Muslim. But this experiment went awfully wrong from the very beginning, mostly because of the rebellious Croats, who immediatelly started opposing the Serbian royal dynasty, and seeking their separation from the Kingdom.
After the WWII, it was decided to keep Yugoslavia with the same objectives - as a barrier to the influences of Turkey, Russia, Germany, and Vatican in the region - but only this time with the imposed communist rule. After the fall of communism in the late 1980s and early 1990s, the forces which were keeping Yugoslavia together broke apart, and eventually a civil war was imminent. Turkey was backing Muslims in Bosnia and Muslim Albanians in Kosovo, Russia was backing Serbs in Croatia and Bosnia, and Germany and Vatican were backing Croats and Kosovo Albanians in their seek for independance. The Yugoslav People's Army could easily overrun the country and declare a martial law, but its main generals were war profiteers who didn't want to end the civil war, but to prolong it in order to make profit in smuggling weapons and oil and cigarettes and different stuff.