Former North Korean diplomat declares run for National Assembly in South Korea

SEOUL, South Korea -- A high-level North Korean official who defected to South Korea in 2016 plans to run for a seat in South Korea's National Assembly elections this April. If elected, Thae Yong-ho would be the first-ever former North Korean official to become a lawmaker in the South.

A former deputy ambassador at the North Korean embassy in London, Thae caught public attention as he was spotted accompanying North Korean leader Kim Jong Un's elder brother Kim Jong Chul to a Eric Clapton concert in London in 2015. He is the second-highest North Korean official in history to defect. The late Hwang Jang Yop, a former senior official in the regime widely credited with crafting North Korea's founding principle of Juche, or self-reliance, defected in 1997.

"I stand before you as a proud South Korean citizen that wants to do his part in deciding the future of our country," Thae told a group of foreign press members in fluent British-accented English on Wednesday in Seoul. "This is also a great opportunity to show the North Korean people our democracy and freedom."

Thae said he believes thousands of North Korean laborers, students, diplomats and entrepreneurs currently working abroad outside of North Korea will get to see how democracy works and become interested in South Korean elections.

"Breaking down communism and totalitarianism will take more than coercive force," Thae said. "This election, and my campaign, can be a game-changing opportunity for our peninsula."

Since his defection four years ago with his wife and two sons, Thae has been protected by the South Korean government for fear of assassination or terror by North Korean infiltrators. He has occasionally appeared on local TV and wrote articles on North-South issues, gradually increasing his voice in recent months on human rights for 33,523 North Korean defectors living in the South. Thae's YouTube Channel has drawn 137,000 subscribers and is growing fast.

Earlier this month, Thae joined the main opposition United Future Party, to run for the National Assembly election in April. The conservative party's official in charge of candidacies announced that Thae "was the first among the defectors who volunteered to confront the voter's judgment by running for the elections." Unlike the proportional representation candidates, Thae has to compete with other party nominees. Thae is awaiting the United Future Party to designate which local constituency he will be competing in.

Thae said the turning point for him came when he saw the image of two North Korean fishermen apprehended in South Korean waters being handed over to North Korean authorities, against their will. The forced repatriation by the South Korean government was a controversial issue. North Korea claimed they were criminals who fled, but many, including Thae, in the South insisted that is propaganda in disguise and asylum should have been granted to the young men.

"As long as we are human beings, we should save the people who want to be saved," Thae said. "That is humanity. That's why I want to change the law."

Thae said he wants to help the international community understand the real face of the North Korean regime and get over the "total failure and diplomatic catastrophe" of Trump's engagement efforts with Kim Jong Un.

But he said he realized that he needed a political platform to have his voice heard by foreign counterparts. For example, since he is a defector from North Korea, China bans him from entering the country. Thae wants to explain to Chinese officials where North Korea stands in nuclear negotiations, help the Japanese resolve the issue of civilians abducted by the North, and talk to U.S. senators and congressmen about why Kim Jong Un will "never give up its nuclear weapons program."

Thae's race will be a tough one. He faces much criticism from South Korea's ruling democratic party and its supporters in favor of rapprochement with the North.

"There are people here who say I shouldn't talk about human rights or campaign for the assembly seat because Kim Jong Un feels uncomfortable," he told the press, raising his voice. "We should not try to appease the [North Korean] government. That is surely unjust."

ABC News' Hakyung Kate Lee contributed to this report.