Years before anything was publicly disclosed about the nuclear espionage of Julius and Ethel Rosenberg, Klaus Fuchs, and Theodore Hall, the U.S. Federal Bureau of Investigation (FBI) and U.S. Army Intelligence identified Clarence Hiskey, a Manhattan Project scientist, as a Soviet spy helping to provide highly sensitive nuclear weapons information. The two agencies kept watch on a Soviet intelligence officer, Arthur Adams, who was living illegally in the United States and serving as Hiskey's control officer. Despite an extensive investigation, neither Hiskey nor Adams was ever arrested. Although Adams was named in a sensational tabloid newspaper article shortly after the end of World War II and closely shadowed by the FBI, he was able to flee to the Soviet Union. Hiskey was never indicted for espionage. Based on material released from declassified Russian archives and FBI files made available under the Freedom of Information Act, the article tells the story of the first U.S.-based nuclear spy and how he got away with it.

William Albertson, who was executive secretary of the New York Communist Party and a member of the National Committee of the Communist Party USA (CPUSA), was framed as an informant for the U.S. Federal Bureau of Investigation (FBI) in 1964. Only in recent years have newly released FBI records enabled scholars to understand why the FBI undertook the operation and how much damage it did to the CPUSA. In 1964 two leaks from the FBI hinted that the bureau had a high-level informant in the CPUSA who was providing information about secret Soviet subsidies. The leaks were accurate and endangered one of the FBI's most successful intelligence operations, Operation Solo, which involved the use of two brothers, Morris Childs and Jack Childs, who were confidants of CPUSA General Secretary Gus Hall, as key informants. The framing of Albertson was intended to deflect CPUSA and Soviet attention from the real FBI informants to a bogus one. The ploy succeeded. The forged documents the FBI planted convinced Hall and other senior CPUSA officials that Albertson was the FBI informant. Despite Albertson's vehement denials and energetic defense, he was expelled. The CPUSA thought it had eliminated the informant, and the Childs brothers were able to continue in their role until old age forced their retirement in 1977.

Alexander Vassiliev's notebooks with 1,115 pages of handwritten transcriptions, excerpts, and summaries from Soviet Committee on State Security (KGB) archival files provide the most detailed documentation available of Soviet espionage in the United States in the 1930s and 1940s. This article discusses the provenance of the notebooks and how they fit with previously available Federal Bureau of Investigation (FBI) files, KGB cables decrypted by the Venona project, Communist International records, court proceedings, and congressional investigations. As an example of the richness of the material, the essay reviews the notebooks' documentation of Soviet spy William Weisband's success in alerting the Soviet Union to the U.S. decryption project that tracked Soviet military logistic communications, allowing the USSR to implement a more secure encryption system and blinding the United States to preparations for the invasion of South Korea in 1950.