First paragraph of the article:
Thirty years ago this week, on September 26, 1983, Soviet Lt. Col. Stanislav Petrov prevented the use of nuclear weapons by doing nothing. Going against the early-warning procedures in place at the time, he did not report the signals of five American missile launches he saw on his radar screen. On this uncelebrated anniversary of Petrov’s disobedience, national security experts might say that he made a realistic assessment of the threat: Had NATO actually launched a nuclear first strike, it would have used more than five missiles. Even when success entails disobedience and failure, later claims of success in nuclear weapons policy often turn, retrospectively, into praise for realism.