SEOUL — Song Chun-son, a duck farm worker, endured two and a half years in a North Korean labor camp and said she was later coerced to work for its secret police, the Ministry of State Security. Then she defected to South Korea in 2018. She studied to become a caretaker for nursing home patients while working part time as a waitress.

首尔——养鸭场工人宋春善（音）在朝鲜的劳改营中忍受了两年半的时间，她说自己后来被迫为朝鲜秘密警察，即国家保卫省工作。后来，她于2018年脱北，逃到韩国。她通过学习成为了养老院护工，同时还兼职做服务员。

That was until South Korean counterintelligence officers caught up with the details of her past in North Korea, where they said she had been involved in the effort to lure or blackmail North Korean defectors in the South into coming back to the North.

后来，韩国反间谍官员追查到了她在朝鲜的经历，他们说她参与了引诱或勒索在韩脱北者重返朝鲜的行动。

Ms. Song, 44, said she had no choice but to do what the North Korean spy agency asked her to do while she was living there and that she was unaware of being part of a coordinated scheme. Still, South Korean officials arrested her in May on charges of helping the North’s Ministry of State Security. Her case has since provided rare glimpses into the clandestine battle the rival Koreas have waged over North Korean defectors living in the South.

44岁的宋春善说，住在韩国期间，她别无选择，只能做朝鲜间谍机构要求她做的事情，而且她不知道自己是协调计划的一部分。尽管如此，韩国官员还是在5月将其逮捕，指控她为朝鲜的国家保卫省提供协助。在那之后，她的案子提供了一个罕见的机会，让人得以一窥朝韩之间围绕着居住在韩国的脱北者进行的暗斗。

Under its leader, Kim Jong-un, North Korea has plotted to bring North Korean defectors in the South back to their former homeland using whatever means it could, including recruiting people like Ms. Song. But the South’s counterespionage authorities are equally determined to thwart the North’s operation, carefully screening newly arriving defectors from the North, like Ms. Song, to catch anyone linked to its efforts.

在金正恩的领导下，朝鲜一直在密谋利用一切可能的手段，包括招募宋春善这样的人，将韩国的脱北者带回以前的祖国。但韩国反间谍当局同样决心挫败朝鲜的行动，仔细甄别像宋春善这样新来的脱北者，逮捕朝鲜行动的相关人士。

On Tuesday, a court in Suwon, south of Seoul, sentenced Ms. Song to three years in prison. Instead of enjoying her new freedom, she finds herself sitting in a prison cell in the South, having become a pawn in the cloak-and-dagger war between her old and new home countries.

“When I came to South Korea, I confessed to what I did in the North to make a fresh start in the South,” Ms. Song said in an August letter she sent from jail to her sister, also a North Korean defector in the South. “I was coerced to do what I did — but they say that doesn’t erase the crime.”

宋春善在8月从监狱寄给她姐姐的一封信中说：“当我来到韩国时，为了在韩国重新开始，我承认了我在朝鲜所做的一切。”她的姐姐也是一名居住在韩国的脱北者。“我是被迫做这些事的——但他们说这并不能消除我的罪行。”

More than 33,800 North Koreans have defected to South Korea since the 1990s. But since Mr. Kim took power a decade ago, at least 28 of them have mysteriously resurfaced in North Korea. How and why they went back to the totalitarian state they had risked their lives to flee has been one of the great mysteries in inter-Korean relations. (South Korean officials fear that some of the hundreds of defectors who have disappeared in recent years may have also ended up in the North.)

North Korea has used the returnees for propaganda, arranging news conferences where they described how lucky they were to escape the “living hell” they found in the South to return to the “bosom of the fatherland.”

Ms. Song’s arrest showed that South Korea’s counterintelligence officials were not sitting idle. Between 2009 and 2019, they arrested at least 14 North Koreans who entered South Korea as defectors, accusing them of arriving here on spy missions that included plots to bring fellow defectors back to the North, according to government data submitted to the National Assembly.

Ms. Song told the court about how she ended up going to South Korea. A native of Onsong, a North Korean town near the Chinese border, she had been working as a broker, helping North Korean defectors in the South transfer cash remittances to their relatives in the North when the Ministry of State Security recruited her in 2016.

宋春善在法庭上讲述了她前往韩国的过程。她来自稳城市，这里靠近中国边境。2016年国家保卫省招募她时，她在做汇款中介，帮助脱北者将现金汇款给他们在北方的亲属。

Confronting her about her illegal work as a cash broker, the ministry gave her a stark choice: serve time in a prison camp or cooperate with agents. For Ms. Song, who had already been in a labor camp from 2007 to 2009 for the crime of illegally entering China for food in the wake of a famine in the North, the choice was obvious.

汇款中介是非法工作，国家保卫省给了她一个艰难的选择：在劳教所服刑或与特工合作。对于已经进过一次劳教所的宋春善来说，选择是显而易见的。2007到2009年间，她因在饥荒中非法进入中国获取食物而在劳教所服刑。

“She had to cooperate to stay alive, she had no other choice,” said her sister, Chun-nyo, who defected to South Korea in 2019.

“她必须合作才能活下去，她别无选择，”2019年脱北至韩国的姐姐春年（音）说。

In the court hearing on Tuesday that sent Ms. Song to prison, the presiding judge, Kim Mi-kyong, dismissed her appeal, saying that she had helped the North Korean secret police for personal gain as well.

周二的法庭听证会将宋春善送进监狱。在听证会上，审判长金美京（音）驳回了她的上诉，称她帮助朝鲜秘密警察也是为了个人利益。

During her trial, Ms. Song admitted providing a secret police agent named Yon Chol-nam with the telephone number of a North Korean defector in South Korea she had known while working as a broker. She also admitted calling the defector to ask him to help Mr. Yon, lying that the agent was her husband and that he worked for North Korean families trying to reach their defector relatives in the South.

宋春善在受审期间承认，她曾向名叫尹哲南（音）的秘密警察特工提供了一名居住在韩国的脱北者的电话号码，她是在做汇款中介时认识这个人的。她还承认打电话给该脱北者，要求他帮助尹哲南，谎称该特工是她的丈夫，为试图联系在韩国脱北者亲属的朝鲜家庭工作。

With the defector’s help, Mr. Yon located three North Korean defectors in the South, prosecutors said. He tried to persuade them to return to the North by putting their North Korean relatives on the phone with them. One of the defectors, Kang Chol-woo, and his girlfriend, also a North Korean defector in the South, returned to the North through China in 2016 and later appeared on North Korean TV.

检察官说，在脱北者的帮助下，尹哲南在韩国找到了三名脱北者。他试图通过让他们的朝鲜亲属与他们通电话来说服他们返回朝鲜。其中一名脱北者是姜哲宇（音），他的女友也是一名在韩脱北者，他们于2016年通过中国返回朝鲜，后来出现在朝鲜电视台节目上。

In August 2016, the ministry sent Ms. Song to China to spy on North Korean migrants there and on Christian missionaries who helped them flee the North. It gave her a code name: “Chrysanthemum.” But after two years, she fled to South Korea, where she told her debriefers what she did for the North’s Ministry of State Security.

2016年8月，国家保卫省派宋春善前往中国监视那里的朝鲜移民以及帮助他们脱北的基督教传教士。该部门给了她一个代号：菊花。但两年后，她逃到了韩国，在那里她向问讯人员透露了她为朝鲜国家保卫省所做的事情。

“She thought she was cleared when she was released from the debriefing center to live a new life in the South,” said her lawyer, Park Heon-hong.

她的律师朴宪洪（音）说：“当她从问讯中心获释，在韩国过上新生活时，她以为自己是无罪的。”

However, Ms. Song had unwittingly stepped into the fierce spy war over North Korean defectors.

然而，宋春善不知不觉地卷入了针对脱北者的激烈间谍战。

Under Kim Jong-un, North Korea has tightened its control over the border with China, the main escape route for defectors. And it has intensified its crackdown on the South Korean TV dramas and music smuggled from China through which North Korean defectors learned of life in the South.

Partly as a result of these crackdowns, the number of North Korean refugees arriving in the South dropped to 1,047 in 2019 from 2,914 in 2009. The number plummeted to 229 last year, as the pandemic led to further border restrictions.

这些镇压的部分结果是，抵达韩国的朝鲜难民人数从2009年的2914人下降到2019年的1047人。由于大流行导致进一步的边境限制，这一数字在去年骤降至229人。

North Korea has called the defectors “traitors” and “human scum.” But its online propaganda channels have also interviewed family members who tearfully appealed to defectors, telling them that Mr. Kim promised to forgive their crimes if they returned home.

朝鲜称脱北者为“叛徒”和“人渣”。但其网络宣传渠道也对脱北者的家人进行采访，他们含泪呼吁脱北者回家，告诉他们如果他们回家，金正恩承诺会原谅他们的罪行。

South Korea has put its guard up, catching North Korean agents disguised as defectors who entered South Korea on clandestine missions to assassinate fellow defectors or lure them back to the North.

But South Korean counterintelligence officials also have a history of fabricating evidence in their overzealous hunt for North Korean spies. In 2016, South Korea announced the arrival of 12 young North Korean waitresses and their male manager, billing their defections as a major coup against Pyongyang. The manager later said that the South’s National Intelligence Service plotted with him to bring the women here against their will.

但是，韩国反情报官员也有在疯狂追捕朝鲜间谍的过程中捏造证据的历史。2016年，韩国宣布12名年轻的朝鲜女服务员和男经理成功脱北，称他们的叛逃是一场针对平壤的重大叛变行动。那位经理后来说，这是韩国的国家情报局和他密谋计划的，违背她们的意愿将她们带到这里。

“Ms. Song thought she escaped from the grips of the Ministry of State Security when she defected to the South,” said Jung Gwang-il, a North Korean defector who leads No Chain, a civic group working for North Korean human rights. “But waiting for her in the South were counterintelligence officers eager to make what little score they could against the North.”

朝鲜脱北者郑光日说：“宋春善认为，当她叛逃到韩国时，她逃脱了国家保卫省的控制。”郑光日领导了一个致力于朝鲜人权的民间组织“拒绝枷锁”。“但在韩国等待她的是反间谍官员，他们急切地想要在对抗朝鲜上做出一点成绩。”