The United Red Army was founded when various leftist factions in Japan chose to merge into a single revolutionary organization. This group emerged from earlier radical movements inspired by global trends in Marxism and Leninism, as well as militant activism. The idealists believed that the oppressive government and capitalist systems in Japan needed to be dismantled for a socialist society to prevail. In the climate of the late 1960s and early 1970s, student protests and activism were prevalent, setting the stage for the emergence of this formidable organization. The United Red Army adopted a strategy of armed struggle, seeking to incite a revolution through violent means, which they justified as necessary for achieving their revolutionary aims.

The organization, known for its extreme tactics, embodies the radicalization that occurred among youth during this period. Its early actions included bank robberies and the occupation of buildings, aimed at acquiring resources and drawing attention to their cause. However, the internal dynamics of the group were complex; ideological purity tests led to infighting, culminating in a tragic turn of events. Members were subjected to brutal purges, creating a tempestuous atmosphere that contradicted their stated objectives of solidarity and unity.

Despite significant law enforcement crackdowns, the United Red Army's activities on the fringe of Japan’s political landscape resonated with fears about domestic terrorism. The group's tactics and ideologies posed a significant challenge to Japan's societal norms and governmental authority. They challenged the status quo and incited debates over police power and civil rights. The foundation of the United Red Army marked a crucial point in Japan's sociopolitical history, influencing future left-wing movements and changing the landscape for activism in the country.