North Korean security officials are eager to use any and all possible means to unravel the opposition.
Sometimes a close friend becomes a snitch shop.

He suspects that Jun Sang’s best friend in high school was the government’s informant. When Junsan returned from Pyongyang, he began to shout out at the government and there was a sign that Junsan was trying to reconcile. (Barbara Demick, Nothing to Envy:Ordinary Lives in North Korea)

The North Korean secret police’s National Security Service is using various means to try to unravel the opposition.

Immediately after moving, some people knocked on my door. When I came out, she was very amiable, a very kind man, and started telling something unexpected to her. Some Americans pay a lot of money to return the remains of a soldier who died in the Korean War. He wants to carry it across national borders, so he might help him.
The Guard uses a variety of other hands. Suddenly, she appears in a kindergarten and asks the children there, cheerfully, “What was the most interesting movie you’ve watched recently?” A kid named a Korean blockbuster movie that he saw on an illegal videotape and was happy to talk about its content.
The child’s family, who had a high social status, was in trouble. (“A girl with seven names”)

The following is a “deception” by very elaborate authorities for university scholars.

This happened in the 80’s. The North Korean government, which has suffered from agriculture slump, has given unified research agendas to three universities, including the People’s Economic University. The theme was farm management. He was ordered to study the following three cases assigned to each university: 1. If the current group farm is maintained; 2.If private ownership is introduced and the ratio is split equally between the group farm and the farm. 3.When collective farms are abolished and privately owned. He said, “Let’s study freely” the increase and decrease of the yield in each case and the impact of each management method on politics. That is the agricultural policy that is at the heart of the country.
In addition, researchers have already realized that the biggest cause of poor farming is farm management. Researchers at each university were immersed in research themes in response to the “new breeze”. Eventually, the research results were announced.
In cases 2 and 3, production is expected to increase by at least 20 to 30 percent. Moreover, maintaining national control over fertilizer, agriculture and agricultural machinery will not disrupt the socialist system. Here are the conclusions drawn from free research: However, the group of researchers at the universities responsible for cases 2 and 3 was crushed. The reason was “we did anti-revolutionary research.” I don’t know where he was after. It was a kind of excitement. (Lee Yonghe, “North Korea: The Night of a Secret Assembly”)

The following similarly elaborately “fools” university scholars.

In the early 1970s, Kim Jong Il was emerging. Along with the portrait of President Kim Il Sung, portraits of his son Kim Jong Il have been displayed in each family. Of course, it cannot be a voluntary act of the common people. It is under the direction of the authorities.
At such time, such a notice was issued by the authorities to each work unit. “You should only give a portrait of Marshal Kim Il Sung, and give my own portrait,” said Kim Jong Il. It is up to the people to think about this, and to write frankly. “This is also the opinion of Kim Jong Il, and it is natural to do so,” wrote a college teacher frankly.
This led to calamity. He was accused of being a “rebel thinker” and had to leave college. It is “Expulsion” Pyongyang. (Ibid.)

In some cases, censorship groups deceive and defeat residents.

The censors used various means to achieve brilliant results. In particular, the flyer is nothing more than a hook. “Confess the crimes committed against the state ten years ago. Forgive those who confess honestly.” The censorship handed out such a self-criticism to all families. He confessed to any criminal offense. Anyone who truly receives this and confesses honestly is drowned.
Another trick is recommending a sniffer. “Also, honestly complain about what you see and hear about others, and you’ll make your sins lighter.” This leads people to write things that they don’t always like. With this irresponsible chikuri as material, the censors arbitrarily took ordinary people. The censors looked at each household’s income and expenditure if it wasn’t enough. For example, calculate your monthly income and compare it to household items. How much do TV and radio do? If they do not balance, they will be confiscated, saying they are illegal.
(Shiraeikichi “North Korea Bad Diary”)