Omigod! I thought we were a couple of generations past the old "Who Promoted Peress," "Who Lost China," "GEN George Marshall the Communist Agent" stuff! Most everybody was pro-Soviet (or at least pro-Red Army) in the 40s (aka WWII). Dean Acheson was a stand-up guy against the communists after 1945. And he mocked Bobby Kennedy's timid argument against attacking Cuba in Oct 62 (Bobby: "But, it'd be like Pearl Harbor!")
Acheson's defenders have promoted that view of Acheson since the Alger Hiss trial--most recently in Douglas Brinkely's Acheson biography. It doesn't fit the complete record on Acheson's actions. As I indicated in Part 1 (please refer to the footnotes), Acheson was not anti-Soviet in 1945, but continued to promote sharing nuclear technology with the Soviets into 1946, and was named as a Soviet agent in an FBI file of that year. He reluctantly became anti-Stalinist towards the end of 1946, but was never ideologically committed to anti-Communism (he was opposed to Stalin rather than Communism); rather, he pushed for a US-Chicom alliance at that time (at the same time Soviet agents were promoting the same position), and opposed John Foster Dulles' aggressive anti-Communist policies in the 1950s--most likely for partisan reasons (Dulles felt that Acheson opposed whatever he suggested simply for the sake of being contrarian). Also Acheson went to lengths to cover up his pre-1946 Communist activity by defending Alger Hiss and others, and he continued to advise Felix Frankfurter on a daily basis during the Truman administration. His post-1946 behavior was paradoxical. My interpretation is that he probably wasn't a Soviet agent after 1946 but he often continued to advance Soviet ends through his contrarian partisanship and his lax security policies. I'm not sure what was going through his mind during the Cuban Missile Crisis, but I tend to think that was more a reflection of his personality than his ideological views. Acheson enjoyed being confrontational.
Also on this:
"Most everybody was pro-Soviet (or at least pro-Red Army) in the 40s (aka WWII)."
No, they weren't. Most of the Russian specialists in the State Department who'd had experience with the Soviets since the 1920s-1930s were anti-Soviet. But they were squeezed out of power by a pro-Soviet faction over the course of the Roosevelt administration and the early years of the Truman administration. Soviet ambassador Maxim Litinov exerted pressure on Sumner Welles towards this end in spring 1943, and Anatoly Gorsky and Henry Wallace made a renewed push in this direction after Roosevelt's death in 1945.