Was 1983 the year the Cold War came closest to nuclear war?

That is the claim, and it is disputed. Two events, a few weeks apart, are behind it. On 26 September 1983 the Soviet early warning system Oko reported one intercontinental missile launched from the United States, with four more behind it. Soviet strategy for such a warning was an immediate counter-attack (launch on warning). The officer on duty, Lieutenant Colonel Stanislav Petrov, decided to wait for corroborating evidence, none of which arrived, rather than immediately relaying the warning. He reasoned that a US first strike would be massive, so five missiles seemed an illogical start. The alarm was later traced to a rare alignment of sunlight on high-altitude clouds and the satellites' orbits.

In November 1983 NATO ran Able Archer 83, an exercise simulating nuclear escalation. Some Soviet Politburo and military members came to believe it was a ruse of war covering a genuine first strike, and the Soviet Union readied its nuclear forces and put air units in East Germany and Poland on alert. The threat ended when a US general advised against responding to that activity and the exercise concluded on 11 November.

How close was it? Some scholars argue that Able Archer 83 was one of the times when the world came closest to nuclear war since the Cuban Missile Crisis; others have disputed this.