Your question is based on an incorrect premise; there were plenty in the US who, over the course of the Cold War, believed that tactical weapons could be used without inevitable escalation. Similarly there were those in the USSR who concluded that escalation was too dangerous. The tactics of both nations were similar-enough during the Cold War — they both developed huge stockpiles of both tactical and strategic nuclear weapons, as well as doctrines and plans to use both. There is no simple answer to the question because in neither cases was the development of their doctrines all that simple and straightforward, and it changed with both technological developments as well as strategic ones (e.g., relative sizes of arsenals).

The best overall book on the evolution of US nuclear strategy is the appropriately-titled Evolution of Nuclear Strategy by Lawrence Freedman. It's the first place to turn if you want to see how US thinking changed over time, and the many varieties of theory that at times occupied it, which includes both mutually assured destruction, deterrence generally, and the idea of "limited nuclear war."