killed or died in Axis concentration camps. (e.g. Slovene collaborators put together lists of Slovene political prisoners and assisted in their deportation to Nazi concentration camps). Serbia was invaded and partitioned by Germany, Italy, Hungary, Bulgaria, and the NDH. Rump Serbian territory was placed under German military administration, with the help of a civil puppet government led by Milan Nedić. In response to a large, Communist-led uprising in Serbia, the German military in just two months executed 30,000 Serb civilians and Jews. Remnants of the Royal Yugoslav Army organized the Serbian monarchist Chetniks were the first resistance movement. The Chetniks were led by Draža Mihailović and were recognized by the Yugoslav government-in-exile. While it was anti-Axis in its long-term goals and engaged in marginal resistance activities for limited periods, the Chetniks also engaged in collaboration with the occupying forces for almost all of the war. The Chetniks were partners in the terror and counter-terror that occurred in Yugoslavia during WWII. The terror tactics against the communist Partisans and their supporters was ideologically driven. The Chetniks sought the creation of a Greater Serbia by cleansing non-Serbs, mainly Muslims and Croats, from territories that would be incorporated into their post-war state, and carried out genocide against Muslims and Croats during this period. According to Žerjavić, an estimated 18,000–32,000 Croats and 29,000–33,000 Muslims were killed by the Chetniks. The Communist Party of Yugoslavia (KPJ) remained largely inactive while the Molotov–Ribbentrop Pact between Germany and the Soviet Union was in effect. During this period, the Soviet Union pursued friendly relations with Germany and considered recognizing the NDH. Following the Nazi invasion of the Soviet Union in 1941, Communist-led Yugoslav Partisans issued a call for an uprising. Josip Broz Tito was the supreme commander of the Partisan forces. The Communist leadership saw the war as an opportunity for a revolution and an establishment of a Soviet-style totalitarian regime. Until the 1st half of 1942, during a period described as "red terror", their units were engaged in the mass killing of perceived class enemies, a policy that threatened their popular support. The leadership then changed this approach and focused less on class warfare, until the postwar period. The Chetniks and the Partisans, the two main guerrilla resistance units, initially cooperated against the Axis, but their cooperation soon fell apart, and they turned against each other. Due to the Chetniks' collaboration with the Axis, Allied support shifted