I am trying to be as respectful as possible here, but saying that authoritarianism doesn't exist is an absolutely insane take. Obviously the CIA did a lot to try and stop communism, we all know that. And why wouldn't a state want to suppress dissent, do you think that all "communist" regimes were these perfect, do nothing wrong utopias? Of course a state wants to suppress dissent, it gives them more control over their people, Governments are greedy, even if they claim to be communist. I don't think the extent of mass surveillance, forced propaganda, censorship, and imprisonment could be justified by "stopping a foreign entity. Here are some examples of the things authoritarian "communist" regimes did to supposedly "fight foreign powers".

Soviet Union (USSR): Under the leadership of Joseph Stalin, the Soviet Union carried out numerous purges and suppressions of dissent. The Great Purge in the late 1930s resulted in the execution or imprisonment of millions of people, including political opponents, intellectuals, military officers, and ordinary citizens accused of disloyalty or counter-revolutionary activities. The state employed the secret police, censorship, forced labor camps (Gulags), and surveillance to maintain control and suppress dissent.

People's Republic of China: The Chinese Communist Party (CCP) has a long history of suppressing dissent. During the Cultural Revolution (1966-1976), Mao Zedong mobilized student groups known as the Red Guards to target intellectuals, artists, and political opponents. Many individuals were persecuted, imprisoned, or killed. In more recent times, the Chinese government has tightened control over the media, the internet, and social media platforms, censoring content, monitoring online activities, and imprisoning activists and dissidents who challenge the party's authority.

Cuba: The Cuban government under Fidel Castro and his successors has been known for suppressing dissent. The regime has restricted freedom of speech, assembly, and the press, controlling the media and limiting access to information. Independent journalists, activists, and political opponents have been subject to harassment, imprisonment, and surveillance. The government also tightly controls access to the internet and social media platforms.

North Korea: The totalitarian regime in North Korea, led by the Kim family, has implemented strict controls on information and dissent. The state maintains a pervasive surveillance system and enforces ideological conformity through propaganda, censorship, and forced indoctrination. Any form of dissent or criticism of the regime is severely punished, with individuals and even entire families sent to political prison camps.

East Germany: During the existence of the German Democratic Republic (GDR), the ruling Socialist Unity Party suppressed dissent through surveillance, censorship, and repression. The Ministry for State Security, commonly known as the Stasi, maintained a vast network of informants and spies to monitor citizens' activities and control dissent. The government restricted travel, controlled the media, and imprisoned those who challenged the state's authority.

Most suppression of dissent was done to citizens of the state. If you think that any of this can be justified by "fighting foreign powers", you are absolutely delusional.