It is taken almost as gospel that deterrence was (and remains) an effective strategy, however this document reveals a huge flaw with that conclusion and how it was practiced. The US “knew” that they would only act rationally and not initiate a first strike nor a “launch on warning” attack but were ok with (and maybe even encouraged) the Soviets thinking that we might not act rationally. If you are led to believe that US leaders might not always act rationally when it comes to Nuclear war then you can’t on them to also want to avoid Mutually Assured Destruction - a decidedly rational proposition. 

This exchange taken form the minutes of the National Security Council meeting on December 22, 1975 discussing the deterrence implications of signing the SALT II treaty. 

(Almost) tragically my statement is confirmed in 1983 when the USSR nearly launches a full scale nuclear attack on the US as they fear an unprecedentedly massive NATO military exercise might actually be an attack. A 1990 report (declassified 2012) looking for lessons learned from that incident, The Soviet “War Scare,” affirms this in its conclusion: