Soviet photographers, especially those involved in the propaganda machine (press, photojournalism, etc) had access to the best photo equipment of their time. That included Leica, Contax, and larger cameras. This was true before the war and all the way to the end of the USSR. Professionals used Nikon SLRs when we, simple people, used Zenit-E;-).
A side word about Leicas.
There is a famous wartime 'song of wartime corespondents' (journalists), also known as 'С "лейкой" и блокнотом' - with a Leica and a notepad. I actually learned the word 'Leica' from this song.
The composer, M. Blanter, is the same who wrote 'Katyusha'.
You can listen the song here
http://www.youtube.com/watch?v=eL3n_hnl-44&feature=relatedSecond line starts - "s leikoi i bloknotom".
I also found this comic performance of the song (could not resist)
http://www.youtube.com/watch?v=P1KzYFI5YrQ&feature=related