North's Korea's No. 2 diplomat in the U.K. has defected to South Korea — one of the highest-ranking officials to do so, according to South Korea.

A spokesman for South Korea's Unification Ministry announced Wednesday that London-based Thae Yong Ho had recently arrived in the country and that he and his family are now under government protection, the Yonhap News Agency reports.

As NPR's Frank Langfitt tells our Newscast Unit, South Korean officials say Thae had grown disappointed by the government of Kim Jong Un:

"They also say Thae's defection signals weakening support for Kim among North Korean elites."Thae was the second-ranking diplomat in the United Kingdom behind North Korean Ambassador Hyun Hakbong."North Korea watchers say Thae could provide valuable intelligence on political support for the regime as well as the state of North Korea's nuclear program and economic reforms."The highest ranking North Korean official to defect to Seoul was Hwang Jang Yop, who was high up in the ruling Workers' Party."He fled nearly two decades ago and died in 2010."

Several analysts questioned whether a defection by Thae signals discontent with the current regime.

The New York Times reports: "Cheong Seong-chang, a senior North Korea analyst at the Sejong Institute in Seoul, said that isolated defections like Mr. Thae's should not be taken as an indication of instability in the North, and that there was no sign of an organized challenge to Mr. Kim's rule."

The Associated Press spoke with Chang Yong Seok at Seoul National University's Institute for Peace and Unification Studies, who said that "senior North Korean officials have defected before, but these have all been isolated cases that weren't followed by a chain of defections by other officials."

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