The Ustaše was a fascist political party in Croatia that was active from 1929 to 1945. The party was founded by former Party of Rights secretary Ante Pavelic in the aftermath of King Alexander I of Yugoslavia's dissolution of all parties in Yugoslavia, and the party's ideology was a blend of fascism, Catholicism, and Croat nationalism. The Ustaše supported the creation of a Greater Croatia that would span the Drina River and extend to the border of Belgrade, and it emphasized the need for a racially "pure" Croatia. The party promoted genocide against Serbs, Jews, and Romani people, and the persecution of anti-fascist Croats and Bosniaks. The Ustaše viewed Bosniaks as Muslim Croats, and therefore promoted Islam as well as Catholicism seeing Islam as the religion which kept true the blood of the Croats.
The Ustaše functioned as a terrorist group during the 1930s, launching a failed uprising at Lika in 1932 and carrying out several train bombings and assassinations. In 1934, the Ustaše and IMRO even succeeded in killing King Alexander. During World War II, the Ustaše collaborated with Fascist Italy and Nazi Germany, and they were given control of the Independent State of Croatia puppet state on 10 April 1941, with Pavelic leading it. Pavelic created a government system similar to that of Italy and Germany, and the Ustaše enacted anti-Serbian and anti-Semitic policies that resulted in the deaths of 100,000 Serbs and Jews in concentration and extermination camps, and several hundred thousand Serbs and tens of thousands of Jews and Roma were tortured and killed elsewhere. The Ustaše's cruelty led to the growth of both the Chetniks and Yugoslav Partisans, and even the Germans attempted to calm Pavelic.
In 1945, Ustaše politicians Mladen Lorkovic and Ante Vokic attempted to oust Pavelic from power and realign the Ustaše towards the Allied Powers, and the Ustaše were ordered to continue fighting even after the German surrender in May 1945. Many of the Ustaše went underground or fled to countries such as Canada, Australia, Germany, and South America with the assistance of Catholic churches and their own grassroots supporters. In 1956, Pavelic founded the Croatian Liberation Movement in exile in Argentina.