South Korean officials agree that some of the North Koreans may have returned out of desperation after failing to adjust to life in the South. But they also suspect that some were abducted back to the North after they were lured to China. North Korean agents have tried to blackmail defectors in the South, using their relatives in the North as hostages, they said.

The returning defectors are a propaganda boon for Mr. Kim.

His government has organized news conferences in Pyongyang, where the returnees claimed that human smugglers or South Korean spy agents cheated or kidnapped them to the South. They invariably thanked Mr. Kim for giving traitors like them a second chance. The United Nations has long criticized North Korea as one of the world’s worst human rights violators.

Under Mr. Kim, the North has tightened control along the border with China, the main escape route for defectors. The number of North Korean refugees arriving in the South dropped to 1,418 last year from 2,706 in 2011, according to the Unification Ministry. It has also intensified the crackdown on South Korean movies and TV dramas smuggled from China through which North Korean defectors said they learned of life in the South.

“In the South, where money ruled, there was only physical and psychological pain waiting for people like me who had betrayed their fatherland and fled,” Ms. Lim said in an apparent warning to North Koreans who might be dreaming of leaving for the South.

Ms. Lim arrived in South Korea in 2014.

From December, she had been among scores of mostly young female North Korean defectors who have tried to build careers on cable TV talk or reality shows. They often appear in North Korean dresses and sing North Korean songs.

Speaking in their unmistakable North Korean accents, these women share often funny or tearful episodes of life in the famine-struck Stalinist state or their dangerous journeys for freedom. A show called “Love of South and North” matches North Korean women with South Korean men, placing them in a romantic situation.

These entertainment-driven programs, which often advertise “beauties from the North,” are accused of airing sensational yet unconfirmed allegations from the defectors. But they are also credited with helping South Koreans understand the lives of ordinary people in the North, a neighbor that has seldom generated interest among South Koreans despite its growing nuclear and missile threats.