While the end of WWI and the eventual repurcussions of the Versaille Treaty obviously provoked WWII, I think 1918 and its period are too early to describe the true nature of the Cold War.
I would say the Cold War began as soon as Churchill and Stalin began their mutual mistrust, which would have been early in WWII. The U.S. may have reinforced this situation by the nature and comparison of Lend Lease to the British, and Lend Lease to the Russians. A further estrangement occured, as alluded to earlier, when Eisenhower agreed to invade North Africa rather than France. Opening the Western Front early, regardless of how ill-prepared the western Allies were for the effort, would have made a strong statement to the Russians that the British and U.S. wanted to be equal partners in the conflict on the continent, instead of what the Russians perceived as England protecting "colonial" interests in N. Africa and the Med before invading France. While the facts suggest that an Allied landing in France in late '42 or early '43 would have been a bloodbath, the significance of the gesture to the Russians, I contend, would have been a step forward in reassuring Stalin that he had allies with which he could place confidence in. Does this mean we were wrong for delaying Overlord until mid-44? From a military standpoint, no question it was the right thing to do. But, from a political view, especially with respect to Russian perception, I believe it began the spiral towards the ultimate distrust that provided the foundation of the Cold War.
So often, wars are started because humans are, at their core, selfish, infantile, ignorant, and allow these personal emotions to carry over into their judgements on how to govern themselves. Communism, just as any other governmental system, ideally works just as well as Democracy. A benevolent dictatorship in ideal execution is probably the most effective governmental system imagined. My personal belief, although perhaps incorrect, is that Democracy dilutes the ability of any one individual to decisively affect the life, liberty, and happiness of another. By reducing the human variable, democracy works--not perfectly, but functional none-the-less. Communism as perceived by Lenin, probably was similarly functional. At the end of the day, people just want to be left alone in order to work, feed and raise their families in peace, and live. I believe there are many systems that can accomplish this. American "democracy" has worked for us, but surely is not a panacea for the rest of the world.
I believe the Cold War was an equal balance of a Western perception that the Soviet block was bent on supremacy, just as the Soviets perceived an attempt by the West to dominate politically. This mutual mistrust and fear, I propose, emerged during the conduct of WWII.