The path to achieving permanent peace on the Korean Peninsula is through peaceful means, he said, and maximum engagement should be applied to both the North Korean leadership and its people.

Thae defected to South Korea last year with his wife and two sons.

He said he was motivated by a desire to grant freedom to his children, who had already had a taste of the outside world in Britain.

"I decided that the best gift which I may give to my son is the freedom which is so common to everyone here," the former diplomat said. "I strongly believe if we educate the North Korean population we can change North Korea."

While the "reign of terror" of North Korean leader Kim Jong-un can't be stopped, more can be done to disseminate outside information into the reclusive nation, he added. Young North Koreans have started calling SD cards "nose cards" because they can be smuggled into the country inside one's nostrils.

Thae also spoke at length about Kim's rise to power following the sudden death of his father and then leader Kim Jong-il in 2011. Faced with insecurities about the legitimacy of his rule and the failure of an economic reform campaign, Kim proceeded to purge numerous officials, including his once powerful uncle Jang Song-thaek, and accelerate the regime's pursuit of a nuclear-tipped missile capable of striking the US.

"Whenever he watched the senior leaders' attitude around him, he thought there was a little looking down upon from the senior leaders because he was the third son," Thae said. "A lot of the North Korean population don't know that he is the third son."

He added: "Even after 5 years of power, he hasn't told the date of his birth, his mother, and he could not show his childhood photos with (his grandfather and founding leader) Kim Il-sung."

Thae, whose visit was made possible by invitation of Rep. Ed Royce (R-CA), is scheduled to testify before the House Foreign Affairs Committee on Wednesday. Royce serves as chairman of the committee. (Yonhap)