Pyongyang, North Korea (CNN) Thae Yong Ho says he defected from North Korea for the future of his family.

His sister says it makes him a "rotten scumbag... not even an animal."

Thae, the former deputy ambassador at the North Korean embassy in the United Kingdom, became the highest-ranking defector in nearly 20 years when he left his post last year

He told CNN he defected because he could not miss the opportunity to "cut off this slavery chain" for his sons.

But Thae, who fled with his wife and children, worried about his family back home. Relatives of defectors are often sent to prison camps or used by the regime as propaganda tools.

"Kim Jong Un abuses even the love between parents and children," Thae said.

But back in North Korea, Tae Ok Ran, Thae's sister, calls that answer "100% evil propaganda."

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Not one person in the family has been punished, the 57-year-old housewife said.

Thae's brother and sister spoke to CNN for their first-ever interview, which was organized by the government. The pair say it's being done voluntarily.

CNN made Thae aware of the interview but did not get a response.

"It's good to be able to show how we are living," Tae Ok Ran said. "I want to warn him the whole family won't forgive him."

Tae and her brother, Tae Yong Do, say they believe their brother is now a propaganda tool for South Korea and has brought shame upon their family.

Thae's name has been erased as a caretaker on the family tombstone and he has been disowned.

"If I don't wash this sin away by myself, my sons and generations will have to work harder to pay for this," said Tae Yong Do, 53.

Even if families do not view defectors as traitors, contact between North Korean defectors and relatives back home is difficult , if not impossible. It's like losing a member of the family.

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Thae's siblings spoke with a fervor that would have been expected of them, by a government that demands loyalty. North Koreans are often encouraged to report their neighbors for lacking patriotism, defectors say.

"Our society is one big family with leader Kim Jong Un as the father. So because we are all in one big family, we will work harder to repay to the society and the group," Thae's brother said.

The Tae siblings expressed a resolve and reverence to their leader that's common among those on Pyongyang's streets.

"As long as we have that strong slogan, and as long as we are guided by the Supreme Commander comrade Kim Jong Un, we think we can be very victorious in our struggle and the difficulties in the bilateral relationship," Yu Bong Suk, a teacher, told CNN in February.

"We are not afraid," a retired North Korean army officer told CNN last month. "It's a grave situation, but we're ready to counter the American threat with an all-out war and nuclear attack."

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The grave situation he's referring to is the ongoing antagonism and standoff between US President Donald Trump and Kim Jong Un. With Pyongyang's nuclear and ballistic missile programs making rapid progress, Trump has taken a hard line on North Korea, sending warships to the region in a show of force, dispatching top aides to reassure allies of US commitment to the region, as well as engaging China's help.

North Korea says it's not deterred. Sok Chol Won, a North Korean government official, told CNN that the country's nuclear tests would not stop until the United States abandoned what he called "acts of aggression."

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The rogue communist state has also continued to test missiles in the hopes of developing one that can reach the United States.

As President-elect, Trump vowed that wouldn't happen, but Thae says Kim is moving forward.

"He will never give up his nuclear development," he said.