Red squad

In the United States, Red Squads were police intelligence units that specialized in infiltrating, conducting counter-measures and gathering intelligence on political and social groups during the 20th century. Dating as far back as the Haymarket Riot in 1886, Red Squads became common in larger cities such as Chicago, New York, and Los Angeles during the First Red Scare of the 1920s. They were set up as specialized units of city police departments, as a weapon against labor unions, communists, anarchists, and other dissidents.