Oustachis, le génocide oublié

This documentary tells the story of the Ustashe. These Croatians nationalists had been involved in several murderous attacks before WWII until they rose to power in 1941, supported by the Nazis. Then, they led a campaign of ethnic cleansing in the country, while participating actively in the Final Solution. However, their regime is one of the lesser known ones of WWII and their story has almost been forgotten. Why has it been so thoroughly erased?