Thae Yong-ho / Korea Times file



By Choi Ha-young



Thae Yong-ho, former North Korean diplomat who defected to the South in 2016, has quit his job at an institute affiliated with the nation's spy agency, the institute said Thursday. He had been serving as an advisory researcher.



He offered to resign from the position at the Institute for National Security Strategy (INSS) under the National Intelligence Service (NIS), Wednesday, and the institute accepted his resignation immediately after, the INSS said.



Thae's resignation came after North Korea called him "human trash" over his book "Password from the Third Floor" published May 14. While visiting the National Assembly that day, Thae claimed North Korean leader Kim Jong-un will never give up his regime's nuclear weapons, saying Kim is "impatient, impulsive and violent-tempered."



Following the North's accusation, Thae reportedly had thought over his role amid the mood for reconciliation between the two Koreas.



"My decision would be judged in the future, as inter-Korean relations develop. Anyhow, now I am free," Thae was quoted as saying by the JoongAng Ilbo, Thursday.



However, he ruled out external pressure in making the decision. "Nobody pressed me to quit the post. It was my own decision," he said.



He said security support for him would remain the same. The authorities have provided about five security guards and a vehicle to protect him from a possible attack by North Korean agents.



Thae's book became a recent source of friction between the rival Koreas. The North tried the South's patience by abruptly delaying its approval of South Korean reporters' entry to cover the Punggye-ri nuclear test site shutdown event. Without any explanation, the South Koreans had to wait for their entry permit for an extra day.



"It's hard to understand the North's hysteria from an outsider's point of view, but it could be a serious issue for North Korea, considering its political system is centered on the inviolability of Kim," said Park Won-gon, a professor of international relations at Handong Global University.



There was no justification for the South Korean government to silence Thae, since he was not a government official. However, his position at the INSS, which is funded by the NIS, annoyed the North, according to Kyungnam University professor Kim Dong-yub.



His voice has become politicized here. In the Cheong Wa Dae petition system, some netizens demanded the deportation of Thae, while others called for strengthening his security detail.



Thae and his family arrived in Seoul in August 2016, under the former conservative government. Since January 2017, he had worked as a part-time researcher for the INSS.



He has maintained close relationships with conservative politicians. The event on May 14 was organized by Rep. Shim Jae-cheol of the Liberty Korea Party.