Everyone has heard about the Soviet rapes and massacres in occupied Germany, but they also committed large amount of crimes in other countries. For example, in Yugoslavia the politician Diljas complained about crimes committed by the Red Army. In Hungary for example, one witness says "During the siege of Budapest and also during the following weeks, Russian troops looted the city freely. They entered practically every habitation, the very poorest as well as the richest. They took away everything they wanted, especially food, clothing and valuables... every apartment, shop, bank, etc. was looted several times". In China too mass atrocities were committed.
So my question is why did the red army commit so many war crimes in occupied areas, especially compared to other allied armies? Was this allowed in pratice by Soviet Command? Did this have to do with the soldiers' peasant upbringing?
Part 1
In order to answer this question / contextualize this, several factors need to be taken into account:
Reaching its peak in July 1943 with 6.7 million active personnel and only lowering the number slightly to 6.5 million in June 1944 and finally 6.4 million in January 1945 the Soviet Army was a huge organization. Compared to 3.4 million German soldiers in July 1943 and 1.9 million in January 1945 or around 100.000 US Army personnel in July 1944 the sheer size of Soviet Forces makes for a difference in absolute numbers in terms of crimes than other armies. If, say, one percent of US Servicemen in Europe committed some form of crime or infraction against the civilian population, in absolute numbers that would mean 1000 such incidents. In the Soviet case, the same percentage translates into 60000 incidents. Thus, the organizational size of the Red Army must be considered as a factor here. Where there are more people, there are, in many a way, more crimes bound to happen. Of course, there are other factors, which I'll detail below, in play but this one is hugely important as the sheer size of the army leads to a higher number of criminal incidents by correlation.
The Second World War saw a tremendous amount of looting with the Soviets being by far not the only ones where looting was an incredibly widespread phenomenon (that would be the Germans but an in-depth treatment of that would digress too much). What distinguished Soviet policy respectively acceptance of looting from, say, the US Army in Europe was that in the Soviet case, looting was often a necessary act for soldiers to ensure their survival. Not only had the Soviet Union suffered massively in terms of food stuff production through the German occupation, the average Red Army, while better fed than the Soviet civilian, still survived on a sort of ration that British or American soldiers would have found insufficient and unacceptable.
Unlike the Wehrmacht, the Red Army was not ordered to feed itself from the occupied territories but in reality, looting foodstuff had become a necessary step for most members of the Soviet forces to ensure their own survival and ability to fight. Both officers as well as soldiers regarded it as necessary to bolster their diet in order to be able to continue the war, thus and even with explicit orders against looting, it was tolerated by those who otherwise would have been in a position to stop it.
Another factor was that most Soviet citizens, including most officers of the Red Army had never experienced the comparative wealth of even countries like Hungary or Yugoslavia. Neither peasants nor industrial workers nor even the managerial class of the USSR had ever lived under a comparable standard of living as that in urbanized Hungary or even Germany. Given that even US Army soldiers used the war to enrich themselves with goods from Germany on a huge scale to people who had never before seen much less owned a wristwatch e.g., the opportunities offered by looting people who were perceived as complicit in crimes against them and their country (like Hungarians and Germans) presented such an opportunity that it was seen as acceptable on a structural level, mainly because of many of those in charge, a majority also took part in it.
First it must be emphasized here that according to the most recent and extensive treatment of the subject, Wendy Jo Gertjejanssen's PhD thesis Victims, Heroes, Survivors. Sexual Violence on the Eastern Front during World War II, University of Minnesota 2004, there is no evidence that rapes or sexual violence in general was ordered by officers or higher-ups in the Red Army. Rather, specifically sexual violence was seen as a huge problem by the Red Army as an institution as reports from as early as 1943 made by unit and divisional commanders show. But it was seen as a problem of discipline, not as a problem on the principle that rape itself was criminal.
Leaving sexual violence aside for a moment and directing our attention to what can be understood as both political motivated as well as spontaneous non-sexual violence against civilians: While there is also an absence of a systematic policy of violence against political enemies, collaborators and so forth, at least during the initial advance of the Red Army, the outbreaks of these kinds of violence need to be seen within the context of a political system, Stalinism, that had embraced violence against real and perceived enemies as a viable tool of politics. From Katyn to the mass arrests of Armija Krajowa supporters and members to the massacres on German and what-at-the.time-was-German-and-is-now-Polish territory the violence exacted was either ordered from above against real and perceived enemies and collaborators or spontaneous outbursts of violence against the same groups among Soviet soldiers.
Where this violence was ordered by the regime, such as in the case of the mass arrest of 100.000 AK members, 600 of whom died in Soviet custody, it served the political purpose of the regime, namely getting rid of political competitors concerning the future of the Polish state.
Where violence erupted locally and instigated by occupying Red Army troops such in the cases of the town of Przyszowice or in the contested Nemmersdorf massacre, the exact reasons remain unclear but are most likely related to a desire for revenge and only played out on a comparatively small scale for Eastern Front WWII standards (about 60 dead in Przyszowice, at least 10, at most 25 dead in Nemmersdorf). The comparatively local scale and that most of the dead in both these cases were adult males between the ages of 17 and 60 points to the revenge explanation.
The war on the Eastern Front was probably one of the most brutal wars in human history. Germany from the very outset did fight it as a war of annihilation directed against the local populace. The Soviet Union lost more than 20 million people or 13% of its total population, in some areas like Belarus up to 25% of the total population. The experience of everyday life of WWII on the Eastern Front was massively brutal. The vast majority of members of the Red Army were in some ways affected by this, most likely losing one or more family members or friends to the German occupational policies. Paired with a regime that massively played up the theme of collaborationist and the existential danger emanating from the occupation, violence not only seemed to many like an appropriate response but a desire for revenge too.