In November 1983, NATO, during what became known as the Able Archer 83 exercise, rehearsed a nuclear response to a hypothetical Soviet attack on Western Europe. For many reasons—including the anticipated deployment of Pershing II and cruise missiles in Europe—Soviet intelligence was at that time actively preparing for a possible surprise nuclear missile attack by the West. Recently declassified documents show that Kremlin leadership genuinely feared a full-scale war with the West, and that this fear greatly increased the risk of nuclear war in the fall of 1983. But due to failures of the US declassification system, the most important documents about this potentially dangerous nuclear episode remain unavailable, locked in secure facilities. Declassification of those Cold War-era documents, the author writes, could help protect the United States and the rest of the world from nuclear war.