The US Effort To Not Notify the Soviets about Able Archer, Reforger, or Autumn Forge 76 and 77
Immediately after the United States signed the Helsinki Final Act, the US State and Defense Departments spent considerable effort working to find a way not to notify the Soviets about NATO military exercises including Autumn Forge, Reforger, and Able Archer, skirting the key military exercise notification “Confidence Building Measures” procedure established in the Helsinki Accords by the Conference on Security and Cooperation in Europe in 1976.
According to recently declassified State Department cables, US Department of State and Defense political advisors believed that by describing Reforger as “a military movement” rather than a “maneuver,” the US would not be required to notify the Soviets under the terms of the Helsinki Accords.
This revelation is significant because in 1983 the Soviet military had an “an unprecedented  reaction to Able Archer 83” and feared “a surprise NATO attack” during the Autumn Forge, Reforger, and Able Archer exercises. The Soviets may have believed that multiple, non-routine elements Able Archer 83 potentially indicated an actual, rather than rehearsed nuclear release.
(These non-routine elements during Autumn Forge, Reforger, and Able Archer 83 included: a 170-flight, radio-silent air lift of 19,000 US soldiers to Europe, the shifting of commands from “Permanent War Headquarters to the Alternate War Headquarters,” the practice of “new nuclear weapons release procedures,” including consultations with cells in Washington and London, and the “sensitive, political issue” of numerous “slips of the tongue” in which B-52 sorties were referred to as nuclear “strikes.”)
FOIA requests for cables about CSCE notification of Autumn Forge, Reforger, and Able Archer in 1983 have not yet been fulfilled, but the body of documentary evidence I have seen leads me to believe that it is unlikely that the US government reversed course from 1976 and notified the Soviets of their 40,000 troop military
maneuver movement culminating in a simulated nuclear release.
If the US had adhered to the spirit of the Helsinki accords and notified the Soviet Union of the 1983 NATO military exercise, it would have likely done much to advance the Helsinki Final Act’s goal of “reducing the dangers of armed conflict and of misunderstanding or miscalculation of military activities” –including “misunderstanding or miscalculating” a simulated nuclear release for an actual nuclear release.
It is also notable that the declassified text of the proposed press release for Autumn Forge 76 misleadingly describes Able Archer 77 as “ACE-wide command post exercise” –omitting that what the command posts were rehearsing were nuclear release procedures.
Another newly declassified cable (one of more than 300,000 from 1977 that were recently declassified–be sure to read Bill Burr’s terrific summary) includes text from a 1977 State Department Bureau of Intelligence and Research “background paper” on Confidence Building Measures. The backgrounder almost bemoaned the Soviet’s “vigorous approach” to notification of military exercises, which the US and NATO were not mirroring. The State Department seemed to believe that the Soviets were using Confidence Building Measures merely as a Helsinki Accords bargaining chip for an upcoming Conference on Security and Cooperation in Europe meeting in Belgrade, rather than a tool to genuinely reduce military tension.
Of course, the Helsinki Accords were not a treaty, and as such, were non-binding. The Soviet Union certainly also flouted provisions of the Accords. Its poor record in honoring the civil rights portion of the Accords led to the creation of the powerful Moscow Helsinki Group, which monitored (especially Warsaw Pact) compliance.
Unfortunately, we likely have a long time to wait for the 1983 State Department cables to be declassified. Until then we will not know what role the Confidence Building Measures played during the Able Archer 83 nuclear war scare.