On Nov. 2, the Kremlin startled Western scholars by announcing that President Vladimir V. Putin had posthumously given the highest Russian award to a Soviet agent who penetrated the Manhattan Project to build the atom bomb.
The announcement hailed Dr. Koval as “the only Soviet intelligence officer” to infiltrate the project’s secret plants, saying his work “helped speed up considerably the time it took for the Soviet Union to develop an atomic bomb of its own.”
Since then, historians, scientists, federal officials and old friends have raced to tell Dr. Koval’s story — the athlete, the guy everyone liked, the genius at technical studies. American intelligence agencies have known of his betrayal at least since the early 1950s, when investigators interviewed his fellow scientists and swore them to secrecy.
The spy’s success hinged on an unusual family history of migration from Russia to Iowa and back. That gave him a strong commitment to Communism, a relaxed familiarity with American mores and no foreign accent.