The uncle of North Korean leader Kim Jong-un has described how fear of the deadly power politics in Pyongyang drove him and his wife to defect to the US nearly 20 years ago.

In a telephone interview with South Korea’s Yonhap news agency, Ri Kang said they had been deeply concerned by what might become of them in any power struggle that followed the eventual death of Kim’s father, Kim Jong-il.

Ri is married to Ko Yong-Suk, the younger sister of Kim Jong-un’s mother.

“After spending nearly two decades near Kim Jong-il, I had felt the cruelty of power,” Ri said on Wednesday. “I thought it wasn’t such a good idea to live near that.”

Ri and Ko had been tasked with looking after Kim Jong-un while he was studying in Switzerland as a teenager, and rather than return to North Korea they chose to defect to the US in 1998.

Kim’s mother was very ill at the time and receiving treatment in Europe. She would eventually die in France in 2004.

“My wife thought we could get some good treatment for her sister in the US. I went there out of fear of what those in power can do,” Ri said.

It would be another 13 years before Kim Jong-il died, and the transfer of power to Kim Jong-un was relatively smooth.

However, Ri’s worries about the pitfalls of Pyongyang’s power politics were well founded.

After two years at the helm, Kim Jong-un had another of his uncles by marriage, Jang Song-Thaek, purged and executed.

After living in relative anonymity in the US for so many years, Ri and his wife came under the media spotlight last week when it emerged that Ko had filed a defamation suit in Seoul against three South Korea-based defectors from the North.

She is seeking a total of 60 million won ($51,900) for remarks the defectors made on South Korean TV talk shows between 2013 and 2014.

The alleged defamation covers claims that Ko once managed a secret fund for Kim Jong-il, that her father collaborated during Japan’s 1910-45 colonial rule over the Korean peninsula and that she had plastic surgery after defecting to the US.

“My wife has a heart condition and she was very upset by what the defectors said,” Ri told Yonhap.

The interview did not reveal where the couple lived in the US, but Ri said he was running a successful laundry service.

The couple have two sons and a daughter who are attending university in different US states, he added.