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North Korea has made its third generational power transfer. Although Kim Jong-un, or the Cute Leader—officially known as the “Great Successor”—may not really be in charge, the system remains as tyrannical as ever.

The regime rests on several agencies of repression, explains Ken E. Gause, a director at the research group CNA, in a recent study of how the Kim family and allied elites have been able to exploit the North Korean people for more than six decades. His report, “Coercion, Control, Surveillance, and Punishment: An Examination of the North Korean Police State,” is published by the Committee for Human Rights in North Korea.

The Democratic People’s Republic of Korea was formally established in 1948. The country has suffered...