Not mentioned in the article, and almost certainly not known to NATO authorities at the time, but Able Archer 83 came a few weeks after the "1983 Soviet nuclear false alarm incident"[0]. See also "Stanislav Petrov, a Soviet officer who averted nuclear war, has died"[1].

[0] https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alar...

[1] https://news.ycombinator.com/item?id=15273228