Since the late 1920s, the Soviet Union, through its GRU, OGPU and NKVD intelligence services, used Russian and foreign-born nationals as well as Communist, and people of American origin to perform espionage activities in the United States.    These various espionage networks had contact with various U.S. government agencies, transmitting to Moscow information that would have been deemed confidential.   
During the 1920s Soviet intelligence focused on military and industrial espionage in the United States, specifically in the aircraft and munitions industries, and penetrating the mainline federal government bureaucracies, such as the United States Department of State and War Department.[ citation needed] These efforts had mixed results.
One chief aim was the infiltration, placement, and subversion of American political life at all levels of society. Earl Browder, General Secretary of the Communist Party of the United States (CPUSA), served as an agent recruiter himself on behalf of Soviet intelligence.  
Browder later stated that "by the mid-thirties, the Party was not putting its principal emphasis on recruiting members." Left unstated was his intent to use party members for espionage work, where suitable. Browder advocated the use of a United Front involving other members of the left, both to strengthen advocacy of pro-Soviet policy and to enlarge the pool of potential recruits for espionage work. The illegal residency of NKVD in the US was established in 1934 by the former Berlin resident Boris Bazarov.  In 1935, NKVD agent Iskhak Akhmerov entered the US with false identity papers to assist Bazarov in the collection of useful intelligence, and operated without interruption until 1939, when he left the US. Akhmerov's wife, an American who worked for Soviet intelligence, was Helen Lowry (Elza Akhmerova), the niece of CPUSA General Secretary Earl Browder. Recent information from Soviet archives has revealed that Browder's younger sister Marguerite worked until 1938 as an NKVD operative in Europe. She discontinued this work only when Browder himself requested her release from duty, fearful that her work would compromise his position as General Secretary. 
In the 1930s, the chief Soviet espionage organization operating in the U.S. became the GRU. J. Peters headed the secret apparatus that supplied internal government documents from the Ware group to the GRU. Browder assisted Peters in building a network of operatives in the administration of President Franklin D. Roosevelt. This group included Alger Hiss, John Abt, and Lee Pressman. Courier for the group at the time was Whittaker Chambers. Browder oversaw the efforts of Jacob Golos and his girlfriend, Elizabeth Bentley, whose network of agents and sources included two key figures at the Department of Treasury, Nathan Gregory Silvermaster and Harry Dexter White.
One early Soviet spy ring was headed by Jacob Golos. Jake Golos (birth name Jacob Golosenko, Tasin, Rasin or Raisen) was a Ukrainian-born Bolshevik revolutionary and Soviet secret police (NKVD) operative in the USSR. He was also a longtime senior official of the CPUSA involved in covert work and cooperation with Soviet intelligence agencies. He took over an existing network of agents and intelligence sources from Earl Browder. Golos' controller was the head of the NKVD's American desk, Gaik Ovakimian, also known as "The Puppetmaster", who would later serve a key role in the assassination of Leon Trotsky.  Golos was the "main pillar" of the NKVD intelligence network. He had worked with Soviet intelligence from the mid-1930s, and probably earlier. He was not merely a CPUSA official assisting the NKVD (an agent or "probationer" in Soviet intelligence parlance) but held official rank in the NKVD, and claimed to be an oldtime Chekist.
Golos established a company called World Tourists with money from Earl Browder, the General Secretary. The firm, which posed as a travel agency, was used to facilitate international travel to and from the United States by Soviet agents and CPUSA members. World Tourists was also involved in manufacturing fake passports, as Browder used such a false passport on covert trips to the Soviet Union in 1936.  At World Tourist, Golos frequently met Bernard Schuster, an NKVD agent (code name ECHO and DICK) and Communist Party functionary who carried out background investigations for Golos as part of the vetting process of agent candidates.  In March 1940, Golos pleaded guilty to being an unregistered foreign agent, paid a $500 fine, and served probation in lieu of a four-month prison sentence.
Soviet intelligence did not like Golos' refusal to allow Soviet contact with his sources (a measure implemented by Golos to protect himself and to ensure his continued retention by the NKVD). The NKVD suspected Golos of Trotskyism and tried to lure him to Moscow, where he could be arrested, but the US government got to him first. But even then, he did not reveal his agent network. After Browder went to prison in 1940, Golos took over running Browder's agents. In 1941, Golos set up a commercial forwarding enterprise, called the US Shipping and Service Corporation, with Elizabeth Bentley, his lover, as one of its officers.  
Sometime in November 1943, Golos met in New York City with key figures of the Perlo group, a group working in several government departments and agencies in Washington, D.C. The group was already in the service of Browder. Later that same month, after a series of heart attacks over the previous two years, Golos died in bed in Bentley's arms. Bentley then took over his operations (thus the reference in the decrypts to him as a "former" colleague).[ citation needed]
By the end of 1936 at least four mid-level State Department officials were delivering information to Soviet intelligence: Alger Hiss, assistant to Assistant Secretary of State Francis Sayre; Julian Wadleigh, economist in the Trade Agreements Section; Laurence Duggan, Latin American division; and Noel Field, West European division. Whittaker Chambers later testified that the plans for a tank design with a revolutionary new suspension invented by J. Walter Christie (then being tested in the U.S.A.) were procured and put into production in the Soviet Union as the Mark BT, later developed into the famous Soviet T-34 tank.   
In 1993, experts from the Library of Congress traveled to Moscow to copy previously secret archives of Communist Party USA ( CPUSA) records, sent to the Soviet Union for safekeeping by party organizers. The records provide an irrefutable record of Soviet intelligence and cooperation provided by those in the radical left in the United States from the 1920s through the 1940s. Some documents revealed that the CPUSA was actively involved in secretly recruiting party members from African-American groups and rural farm workers. The records contained further evidence that Soviet sympathizers had indeed infiltrated the State Department, beginning in the 1930s. Included were letters from two U.S. ambassadors in Europe to President Franklin D. Roosevelt and a senior State Department official. Thanks to an official in the State department sympathetic to the Party, the confidential correspondence, concerning political and economic matters in Europe, ended up in the hands of Soviet intelligence. 
In the late 1930s and 1940 the OGPU, known as the Political Directorate, used the U.S. as one of several staging areas for multiple OGPU plots to murder exiled Soviet leader Leon Trotsky, then living in Mexico City. It was American Communists who infiltrated Trotsky's killer, the Catalan Ramón Mercader, into his own household. They were also central to the NKVD's unsuccessful efforts to free the killer from a Mexican prison.[ citation needed]
Jacob Albam and the Sobles ( Jack and Myra) were indicted on espionage charges by the FBI in 1957, all three were later convicted and served prison terms. The Zlatovskis remained in Paris, France, where the laws did not allow their extradition to the United States for espionage. Robert Soblen was sentenced to life in prison for his espionage work at Sandia National Laboratories, but jumped bail and escaped to Israel. After being expelled from that country, he later committed suicide in Great Britain while awaiting extradition back to the United States.  
During the Second World War, Soviet espionage agents obtained classified reports on electronic advances in radio-beacon artillery fuses by Emerson Radio, including a complete proximity fuse (reportedly the same fuse design that was later installed on Soviet anti-aircraft missiles to shoot down Francis Gary Powers's U-2 in 1960).[ citation needed] Thousands of documents from the National Advisory Committee for Aeronautics (NACA) were photocopied or stolen, including a complete set of design and production drawings for Lockheed Aircraft's new P-80 Shooting Star fighter jet. 
Joseph Stalin directed Soviet intelligence officers to collect information in four main areas. Pavel Fitin, the 34-year-old chief of the KGB First Directorate, was directed to seek American intelligence concerning Hitler's plans for the war in Russia; secret war aims of London and Washington, particularly with regard to planning for Operation Overlord, the second front in Europe; any indications the Western Allies might be willing to make a separate peace with Hitler; and American scientific and technological progress, particularly in the development of an atomic weapon.
The United States Treasury Department was successfully penetrated by nearly a dozen Soviet agents or information sources, including Harold Glasser and his superior, Harry Dexter White, assistant secretary of the treasury and the second most influential official in the department.   In late May 1941, Vitaly Pavlov, a 25-year-old NKVD officer, approached White and attempted to secure his assistance to influence U.S. policy towards Japan. White agreed to assist Soviet intelligence in any way he could. The principal function of White was to aid in the infiltration and placement of Soviet operatives within the government, and protecting sources.[ citation needed] When security concerns arose around Nathan Gregory Silvermaster, White protected him in his sensitive position at the Board of Economic Warfare. White likewise was a purveyor of information and resources to assist Soviet aims, and agreed to press for the release of German occupation currency plates to the Soviet Union. The Soviets later used the plates to print unrestricted sums of money to exchange for U.S. and Allied hard goods. 
In August 1945, Elizabeth Bentley, fearful of assassination by the Soviet MGB, turned herself in to the government. She implicated many agents and sources in the Golos and Silvermaster spy networks, and was the first to accuse Harry Dexter White of acting on behalf of Soviet interests in releasing occupation plates to Moscow, later confirmed by Soviet archives and former KGB officers.  
President Harry S. Truman's Executive Order 9835 of 22 March 1947 tightened protections against subversive infiltration of the US Government, defining disloyalty as membership on a list of subversive organizations maintained by the Attorney General. Truman, however, was opposed to the McCarran Internal Security Act of 1950, calling it a "Mockery of the Bill of Rights" and a "long step towards totalitarianism". 
- Atomic spies
- Nuclear espionage
- Russian espionage in the United States
- List of Americans in the Venona papers
- Active measures
- Ware group
- Golos spy ring
- Silvermaster spy ring
- Perlo group
- Whittaker Chambers
- Alger Hiss
- Ethel and Julius Rosenberg
- Pavel Sudoplatov
- Lev Vasilevsky
- George Trofimoff
- Farewell Dossier
- Venona project
- The Americans (2013 TV series)
- Haynes, John Earl, and Klehr, Harvey, Venona: Decoding Soviet Espionage in America, Yale University Press (2000) ISBN 0-300-08462-5
- Weinstein, Allen; Vassiliev, Alexander (1999). The Haunted Wood: Soviet Espionage in America: The Stalin Era. New York: Random House.
- Retrieved Papers Shed Light On Communist Activities In U.S., Associated Press, January 31, 2001
- Sudoplatov, Pavel Anatoli, Schecter, Jerrold L., and Schecter, Leona P., Special Tasks: The Memoirs of an Unwanted Witness — A Soviet Spymaster, Little Brown, Boston (1994)
- Christopher Andrew and Vasili Mitrokhin, The Mitrokhin Archive: The KGB in Europe and the West, Gardners Books (2000), ISBN 0-14-028487-7
- Alexander Vassiliev’s Notes on Anatoly Gorsky’s December 1948 Memo on Compromised American Sources and Networks Archived 2009-02-25 at the Wayback Machine; John Earl Haynes, "KGB officer Gaik Badelovich Ovakimian worked as a Soviet spy in the United States from 1933 until 1941 when he was arrested and deported. He was identified in the Venona cables under the cover name Gennady. Elizabeth Bentley reported that Golos identified Ovakimian as his chief contact with the KGB until the arrest."
- VENONA documents NY-MOSCOW, Nos. 1221, 1457, and 1512 (1944)
- Chambers, Whittaker (1952). Witness. Random House. p. 498. ISBN 0-89526-571-0.
- Suvorov, Viktor, Icebreaker, London: Hamish Hamilton Ltd. (1990), ISBN 0-241-12622-3
- Tanenhaus, Sam (1998). Whittaker Chambers: a biography. New York: Random House. ISBN 0-375-75145-9.
- Retrieved Papers Shed Light On Communist Activities In U.S., Associated Press, January 31, 2001
- Cooperation, Time, August 19, 1957
- Feklisov, Aleksandr, and Kostin, Sergei, The Man Behind the Rosenbergs, Enigma Books (2001)
- Schecter, Jerrold and Leona, Sacred Secrets: How Soviet Intelligence Operations Changed American History, Potomac Books (2002)
- Spartacus. "Internal Security Act". schoolnet.co.uk. Retrieved 2011-04-11.
- Chambers, Whittaker (1952). Witness. Random House. ISBN 0-89526-571-0.
- John Earl Haynes, Harvey Klehr, and Alexander Vassiliev, Spies: The Rise and Fall of the KGB in America ( New Haven: Yale University Press, 2009)
- John Earl Haynes and Harvey Klehr, Venona: Decoding Soviet Espionage in America, Yale University Press
- Allen Weinstein and Alexander Vassiliev, The Haunted Wood: Soviet Espionage in America--the Stalin Era (New York: Random House, 1999)
- Soviet Technospies from the Dean Peter Krogh Foreign Affairs Digital Archives
- For new evidence on Soviet espionage in the United States, see former KGB officer Alexander Vassiliev's Notebooks From the Cold War International History Project (CWIHP)
- V.I. Lenin, Terms of Admission into Communist International, (July 1920) First published 1921, The Second Congress of the Communist International, Verbatum Report, Communist International, Petrograd
- Office of the National Counterintelligence Executive. CI Reader: American Revolution into the New MillenniumA Counterintelligence Reader Volume 3, Chapter 1: Cold War Counterintelligence. PDF file. office of the Director of Central Intelligence. Retrieved June 21, 2005.
- Proyect, Louis. Harvey Klehr's "The Secret World of American Communism". Published online May 25, 2002. Retrieved June 21, 2005.
- Robert Louis Benson and Michael Warner, eds., Venona: Soviet Espionage and the American Response, 1939-1957, (Washington, D.C.: National Security Agency, Central Intelligence Agency, 1996)*Vassiliev, Alexander (2003), Alexander Vassiliev’s Notes on Anatoly Gorsky’s December 1948 Memo on Compromised American Sources and Networks, retrieved 2012-04-21
- The Hanford Site, Historic docs, Section 8 - Site Security
- Discouraged, Disillusioned and Duped, Eyewitness account of the era
- Razvedka, Intelligence Information and the Process of Decision Making: Turning Points of the Early Period of the Cold War (1944–1953) Archived March 20, 2006, at the Wayback Machine (In Russian).
- Interview with Ralph De Toladano
- History of Russian foreign intelligence in North America (Russian), Official site of Foreign Intelligence Service (Russia)
- Film: The KGB Connections: An Investigation Into Soviet Operations in North America, 1982, Public domain: Video on YouTube.
- Whittaker Chambers | Witness in the Alger Hiss Case, Anti-Communist, ex-Communist, Spy, Editor, Journalist, Intellectual, Writer, Translator, Poet