I read quite a few Russian materials about WWII and noticed that Russians commonly refer to German soldiers of WWII as фашисты (fascists). Here are some typical examples:
(1) Фашисты заняли правобережье Наро-Фоминска и форсировали реку Нара. (Source)
(2) Он завещал: «Сынок, я бил фашистов под Сталинградом, а ты добей гада в его берлоге!». ... С 14 лет воевал в партизанском отряде, когда фашисты заняли Украину. (Source)
(3) В Краснодаре покажут бой за освобождение города от фашистов. (Source)
This seems very weird because fascists are actually what the pro-Mussolini Italians called themselves at that time, whilst the pro-Hitler Germans called themselves Nazi or national socialists, and there were significant differences between the Italian Fascism and the German Nazism. In particular, the pro-Hitler Germans were focused on purity of their race and made a genocide of European Jews, whilst the focus of Mussolini's ideology was the state rather than the nation. The word Fascism originated from the Italian word fascio (a bundle), which came to symbolize strength through unity, the point being that whilst each independent rod was fragile, as a bundle they were strong.
In the English-speaking world, Nazi is a far more common term to refer to the pro-Hitler Germans of that epoch than fascist is, whilst the opposite seems to be true in the Russian-speaking world. I understand that there were some similarities between the German Nazism and the Italian Fascism, but I am puzzled as to why Russians preferred and still prefer to call the pro-Hitler Germans of that time not what those Germans called themselves, but what Italians called themselves, especially given the differences between the ideologies of the German and Italian states of that time.
Curious, I looked in the transcript of the famous speech of 22 June 1941, the date of the German attack on the USSR, by Molotov, the then-current foreign minister of the USSR, and found that in that speech, he had used the term fascist three times, and the terms Nazi and national socialists - exactly zero times. Based on that speech, my impression is that it was the preference of the Soviet government from the very first day of the Soviet-German war to refer to the German leadership as fascists rather than as Nazi or national-socialists, but I am puzzled as to why the Soviet government had such a preference.
I guess that ordinary Russians of that time simply copied the terminology of their leaders and started to refer to all German invaders, including privates, as fascists, and this tradition seems to have been retained in the Russian language. My impression is that the first associations that come to mind of almost every modern Russian in response to the word фашисты are men equipped with Schmeisser submachine guns and helmets with a "coal scuttle" shape and wearing swastikas on their greenish grey uniforms as well as riding BMW motobikes.
My question: What was the very root cause of preferring the term фашисты (fascists) over нацисты (Nazi) in referring to the German aggressors of WWII in the Russian language? In particular, why did the Soviet leadership have that preference?