Soviet system for predicting nuclear war had lots of complex inputs with an arbitrary thresholdHis worries about a surprise attack were amplified by “one peculiar mode of intelligence analysis,” a KGB computer model to measure perceived changes in the “correlation of forces” between the superpowers, according to the review. The computer went online in 1979 to warn Soviet leaders when “deterioration of Soviet power might tempt a US first strike,” the review says. The computer was at the heart of the VRYAN system, according to the review, and thousands of pieces of security and economic data were fed into the machine. The computer model assigned a fixed value of 100 to the United States, and Soviet leaders felt they would be safe from a nuclear first strike as long as they were at least at 60 percent of the United States, and ideally at 70 percent. Reports were sent to the ruling Politburo once a month.