Also called the “Molotov-Ribbentrop Pact” or the “Nazi-Soviet Pact,” the agreement showed the rest of the world that these two regimes were essentially brutal socialist dictatorships who were happy to work with each other to inflict misery on the rest of the world.
Americans saw this team as a serious threat. The Soviet government was Hitler’s friend, and was also planting its operations inside the United States.
The Communist Party in America, known as the CPUSA, was not an independent organization, but rather an agency of the USSR. The CPUSA was not a political party, advocating platforms and nominating candidates, but rather a terrorist organization, which explicitly stated that it sought the “violent” revolution which would overthrow the government of the United States.
In the political jargon of the era, ‘Brown’ referred to the Nazi party, and ‘Red’ referred to the Soviet Socialist government, as historian Stan Evans writes:
While it lasted, the spectacle of Brown and Red dictatorships in common harness spurred Congress to decisive action, including stern new laws that treated the two as equal dangers. Foremost among these measures was the Hatch Act, adopted in 1939 and further toughened in 1940, which outlawed the hiring or retention of federal workers who advocated the “overthrow of our constitutional form of government,” a rote phrase officially said to mean members of the Communist Party. In May 1941, Congress would adopt a bill of even broader scope, requiring scrutiny of federal workers involved with any “subversive” group whatever. This was Public Law 135, directing that the FBI investigate “the employees of every department, agency and independent establishment of the federal government who are members of subversive organizations or advocate the overthrow of the Federal government,” and report back to Congress.
When the partnership between the Nazis and the Soviet Socialists came to an end in June 1941, Stalin quickly joined the western Allies against the Nazis. This required the United States to set aside its knowledge that Stalin had planted an espionage network in America.
Certain elements inside the U.S. government - elements which had already turned a blind eye to Soviet infiltration in the 1930s - again deliberately ignored growing activity on the part of various Soviet intelligence agencies inside the United States.
While cooperation with the USSR may have been necessary to defeat the Nazis, this cooperation led some to drop their guard concerning Stalin’s intent to undermine the U.S. government.
Between August 1939, when the alliance between the Nazis and the Soviet Socialists was formed, and June 1941, when it ended, there was a period of time when U.S. intelligence agencies could view the USSR and its espionage network more critically.
Prior to that time, and after that time, there were various political influences which prevented a major effort to stop Soviet spy network inside the United States.