I was watching a show on the Military Channel about the Soviets and their nuclear program, and according to the show it seemed like, aside from the first hydrogen bomb, the Soviets were always playing catchup with the US. The US would develop ICBMs, sub-launched missiles, or tactical nukes, and the Soviets would spend years scrambling to match our numbers and methods of delivery.
By the 1970s, both sides came to realize that the present course of armament was costly and insane, and we entered into treaties to try to slow things down. But up till that point, it seems to me that the US had largely dictated how the Cold War would play out. We would think of new ways to deliver nuclear death to the Soviets, and they would eventually match us. The end of the Vietnam War, coupled with the oil crisis and the economic shocks experienced by the US, gave the Soviets a small window in the mid to late 70s where they could have changed the nature of the conflict. Instead, they entered into their own Vietnam in Afghanistan and that, coupled with the fundamental economic limitations of communism, led to the Soviet Union’s collapse.
Despite America’s setbacks in Cuba and Vietnam, it seems to me that the most important aspect of the Cold War was the nuclear arms race, and in leading the way in terms of nuclear weapons technology, the US forced the Soviets to devote lots of time and money on matching our capabilities, such that the Soviets spent an unsustainable and ruinous amount of money to match us. Thus, even though the US spent a ludicrous sum developing an insane level of nuclear deterrent, such spending made sense strategically because it allowed us to dictate the course of the war, at least through the 1970s.