WWII was very weird for the USA. Up until the war, the US government was antagonistic towards the new Soviet Union. In fact, while folks today don't know about it (since most folks are woefully ignorant of history), the Americans (and several other nations) occupied parts of the USSR during the Russian Revolution. After WWI ended, a multinational force came to ostensibly protect their citizens--but in essence, they came to help (unsuccessfully) the Czarist forces to fight the Communists. However, after decades of antagonism or ambivalence, the US found themselves in a strange position--of being allies with the dreaded Ruskies! While this was not at all consistent with US policy both before and after WWII, the government tried very hard in the early 40s to convince the Americans that we LOVED the Soviets and always did! It was simple pragmatism--the enemy of our enemy (the Nazis) was our new friend. Propaganda efforts to put forth this new view of the Soviets was understandable, BUT "Moscow Strikes Back" is, like many pro-Soviet American films utterly ridiculous--even if it DID win an Oscar.
The film originally was a Russian propaganda film. However, the film was given new narration (by Edward G. Robinson) and it drips with glowing praise for the Soviet people and especially good 'ol Uncle Joe Stalin (even if he was responsible for the murder of millions, he was now a regular fellow in this film). And, the film even tries to convince the audience that the Soviets were 'lovers of liberty' and referred to them as 'free people'! Most sane folks today would beg to differ! Stalin was a nut--and ranked just below Hitler on the old evil scale! Because the narration is so unabashedly servile and transparent, I truly hated the film. It's a shame and my bet is the original Soviet version is a lot better (where you'd expect glowing talk of Comrade Stalin). It's also a shame because all the footage was excellent and did a wonderful job of portraying the battle for Moscow as well as documenting German atrocities. But, because the film is so dishonest, I cannot recommend it to anyone unless they understand history and can filter out what is true and what is pure drivel.
By the way, if you DO watch this film, also try watching "The North Star"--a fictional film that portrays Russian folks fighting the Hun. It's actually unintentionally funny and full of silly clichés.