Russia indicates they won WW II.  It's easier than calculating percentages and saying Russia won 51% of WW II and the US won 42% and Britain won 7%.

 Also I figure when a country indicates a win/loss they mean their very specific contribution versus a calculated breakdown.  I learned in grade school that the Russian winter devastated Germany and that Russia became a super power in part to their contribution resulting in the elimination of Nazi Germany expansion.  They won their defensive if I recall correctly in Stalingrad in 43.

 As far as I am concerned Russia did a ton of work, but the US saved civilized Europe, part of that was the US resupplies to Russia through northeastern Siberia.  The other part being a faster and more efficient push into Europe than Russia would have been able to do on their own.

 Russia did not as far as I know assist in North Africa, the US did.

   

 I can see how land-holding is a measurable factor towards victory.  I don't consider casualties to be a strong factor as a lower casualty rate is actually more desirable.  

 I've never done the math but I suppose taking the time in battle, square acreage loss/gain ratio and casualty numbers could be calculated.  I know Stalin did a rather poor job regarding initial defense application and general strategic application was poor.  Shooting your own men, which was common, certainly added to that casualty rate.

 I imagine Russia would have turned things around eventually, but nowhere near as fast without Allied assistance including the US supply drops.  It would have taken decades maybe.

 I don't think the US in exclusivity "won" WWII, I feel it was a combination of forces.  However I don't think especially in 1950's America that anyone thought the US did it alone, but when painting up a banner it was easier to put "We won!" than "We Contributed in part to a Combination of Forces that Won!"  

 One thing I have noticed is that too many people think Pearl Harbor started WWII in general, and many don't know how late D-Day happened.  Saving Private Ryan to many was where WWII began.

Here are a couple other facts that aren't commonly known.   The Soviet Union invaded Poland 3 weeks after the Nazis did.  Stalin and Hitler had a pact at the beginning of the war, they were allies.  After the war the Soviets used many of concentration camps that Nazis built.

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