It was common for both the Germans and the Russians to where white uniforms during the winter, for example during the battle of the bulge or on the eastern front. What about the Americans? White kind of winter camoflague were US troops supplied with?
What’s important to note is that at this time, camouflage was only recently becoming prominent. Leading up to World War 2 military uniforms were becoming more drab in order to blend in with the environment. This is largely due to changing technology. Traditionally, wars were fought with enemy combatants in close proximity to each other. This meant being able to immediately recognize who was friend and who was foe was more important. However, as firearm technology improved, firearms were able to fire rounds much further and much quicker. This led to uniforms becoming more drab. For example, the khaki uniforms allowed the British to blend in to the desert. Soldiers in these times fought in something very similar to the service uniforms you see issued today to the US military. The idea of camouflage as we know it began shortly after Abott Thayer wrote a book on camouflage in the natural world. If I recall correctly, this book was read by many military leaders. However, it still took some time to develop. I say all that to explain that the idea of camouflage was fairly new and the US did not issue camouflage or a winter version of it in World War 2. However, if you look at my first source below you’ll see a picture of US troops attempting to blend into the winter environment during the Battle of the Bulge by wrapping themselves in white sheets.
Sources:
Military Uniforms in America, Volume IV by John Elting
False Colours: Art, Design, and Modern Camouflage by Roy Behrens