ONE OF the most enduring mysteries of the final years of the Cold War was a period of great tension and worry about nuclear conflict between the United States and Soviet Union. The “war scare” of 1983, which unfolded 30 years ago this month, is still shrouded in unknowns, but new information has come to light lately, and the events are relevant and worth pondering today.

In March of that year, President Ronald Reagan called the Soviet Union an “evil empire.” Soon after, he announced the Strategic Defense Initiative, his “Star Wars” quest for a defense against ballistic missiles carrying nuclear warheads. In the summer, the United States carried out a provocative Pacific Ocean naval exercise aimed at the Soviet Union. On Sept. 1, the Soviets mistakenly shot down a Korean airliner, killing all 269 people aboard. In October, Reagan had a detailed briefing on U.S. plans for nuclear war. In November, the ABC made-for-television film, “The Day After,” depicting a fictional nuclear attack on Lawrence, Kan., drew what was then the second-largest audience in history for a single television program. Reagan wrote in his diary that the film left him “greatly depressed.”

In this climate of tension, British intelligence received information from a spy in the KGB, Oleg Gordievsky, that Soviet leaders were growing paranoid about a possible attack. The warning was passed to Prime Minister Margaret Thatcher and then to Reagan. They met in September, and Thatcher found Reagan worried that “the Russians seem paranoid about their own security.” In early November 1983, NATO conducted a nuclear command post exercise in Europe, a simulation of preparations leading to war, known as Able Archer 83, which may have been misinterpreted by the Soviets as real preparation for an attack. Some Soviet military units went on higher alert.

Recently, the National Security Archive at George Washington University has published documents that offer insights about those tense days. The Nuclear Information Service, based in the United Kingdom, also has unearthed fresh materials, which suggest high-level concern, expressed by Thatcher and others, about whether the Soviets possibly misinterpreted Able Archer. The full story is not yet known; much of the actual intelligence reporting remains classified, but the archives point toward a conclusion that the war scare was real.

It led Reagan to conclude, as he described in his diary and memoirs, that the Soviet leaders may have been more paranoid and fearful of the West than he first realized. Reagan was rigid in his beliefs, but when circumstances presented him with new information, he changed. He never again called Moscow an “evil empire.” A few years later, Reagan negotiated the elimination of an entire class of nuclear-armed missiles with Soviet leader Mikhail Gorbachev.

There are lessons here for all who lay claim to leadership in our poisonous and bitterly contested political world today: Take a page from Reagan’s pragmatism. His convictions were strong, but he was able to acknowledge change and recognize his own flawed assumptions. We could use some of that common sense.