"tried to shoot down NATO pilots and at NATO ground troops,"
Hmmmmm, are these the same Serbs who were the only ones in that area of the world that sided with the Americans and her allies during WWII? The Serbs who picked up American pilots who had been shot down and saved their lives from the enemy? Those Serbs?
Soviet Russia, China, Iran and Korea were also allied with the West in WWII - but a lot has changed since then, hasn't it?