John graduated from high school in Puerto Rico, then returned to New York to attend Columbia. He received a bachelor’s degree in political science and international affairs in 1973 and a doctorate in political science in 1982.
His dissertation, about the successes and failures of American intelligence assessments of Soviet military power, became his first book, “The Soviet Estimate: U.S. Intelligence Analysis and Soviet Strategic Forces,” published in 1982.
His marriage to Jill Gay ended in divorce. Along with his partner, he is survived by his daughters from his marriage, Dani and Tasha Prados; his brother, Joe; and his sister, Mary Prados.
After years spent collaborating with the National Security Archive, he joined the organization as a senior fellow in 1997. He soon became its most visible and vocal figure, quick with a quotation or research tip for a like-minded journalist, especially after the terrorist attacks of Sept. 11, 2001 and the Iraq war, events that he feared would herald a new era of government secrecy.
Dr. Prados liked to say that his love for researching and writing was closely related to his second passion: designing board games that intricately simulated historical military conflicts. He created more than 30 such games, with titles involving the Napoleonic Wars, World War II and, of course, Vietnam.
Many of his games have come to be regarded as classics of their genre, none more so than “The Rise and Fall of the Third Reich” (1974), a globe-spanning strategy contest in which players, as the different warring nations, balance economic and military resources against the chance of a dice roll. The game won a Charlie award, the top honor in war game design.
Fans of the game were legion, and far-flung: The Chilean author Roberto Bolaño created a character who mastered it in his novel “The Third Reich.”
