The American ruling class armed the Soviet Union during the "Cold War." This fact is spelled out in detail by Antony C. Sutton in his book, National Suicide: Military Aid to the Soviet Union, published by Arlington House, New Rochelle, New York, in 1973 and online here , excerpts from which I will be asking you to read by indicating the relevant online page numbers. Note that one can quickly get to a given page number online by typing the page number at the page indicator at the very top. (I would like to include these excepts in the text of this article for your convenience, but I have not yet obtained permission to do so from the publisher and am thus limited to only 500 words.)
National Suicide either references directly the documentary sources of its assertions or else refers the reader to the documented sources for those assertions that are in his prior three-volume work, Western Technology and Soviet Economic Development. These three volumes are online here and here and here and are available (directly or indirectly) from Amazon; they are thoroughly documented. I possess all three volumes and have spot-checked the sources and found them to be valid.
If one is inclined not to believe what Sutton asserts in his book, National Suicide (skepticism is, of course, understandable!), I suggest that one obtain the three books of his that contain the additional documentation, and then check out the documents and only then make a decision as to whether or not his factual assertions are well- founded.
Antony Sutton's political view can be succinctly expressed this way: He believed in the free enterprise system, as opposed to "statist" systems such as Nazism and Communism that he condemned for their anti-democratic and oppressive acts. On this basis he supported the United States against its Fascist and Communist enemies. At the same time Sutton opposed capitalists using the government to personally enrich themselves and was therefore very critical of many of America's wealthiest people who, as he discovered and wrote about in other books, had been or were using not only the United States government but also the Nazi German government and the Bolshevik Soviet government to enrich themselves at the expense of ordinary people.
Sutton's books give differing explanations for why U.S. corporate and government rulers armed the Soviet Union. In National Suicide and the prior three volumes it is based on, Sutton says the explanation is essentially some greed and a lot of stupidity. In a later book about Yale's Skull and Bones secret society, Sutton argues that key U.S. rulers support both sides of wars such as (but not limited to) the Cold War in order to become more powerful and control people.
Why did the American ruling class arm the Soviet Union when, supposedly, it was deadly afraid of the Soviet Union? Excellent question! The most compelling answer in my opinion is that the American ruling class wanted a credible foreign enemy with which to control the American people. Such an enemy enabled the rich upper class rulers to pose as the protectors of the nation from the Evil Empire, and in this way make Americans tolerate unjust domination by this upper class, including allowing it to make huge profits from the weapons industry by bilking American tax-payers. (Soviet rulers likewise needed the American bogeyman enemy to control their own people.) Waging the Cold War as an Orwellian war of social control cost many ordinary people their lives and kept most people in great fear, but it was wonderful for the ruling elites.
Preventing "Communist expansion" abroad was also the perfect pretext for the U.S. government to invade other nations and overthrow foreign governments whenever it suited the American ruling class. But for this pretext to be credible, the Soviet Union had to be a serious military power, which U.S. rulers guaranteed by doing what is described below.
Excerpts from National Suicide: Military Aid to the Soviet Union
"Each year in the spring the North Vietnamese have attempted to conquer the South. In 1972, in their latest attempt, a full-scale invasion was launched with various kinds of heavy equipment they had not previously used. The tanks, guns and trucks came from the Soviet Union--and were produced in plants erected and equipped by American and European companies.