Kim Ki-jong, a member of a pro-Korean unification group who is accused of attacking U.S. Ambassador to South Korea Mark Lippert at a public forum, is seen on a stretcher as he arrives at a hospital in Seoul. (Han Jong-chan/Yonhap via Reuters)

The man who authorities say slashed U.S. Ambassador Mark Lippert on Wednesday in a bloody melee has been on the radar of South Korean authorities for years, known as a radical activist who staged violent attacks to promote the reunification of North and South Korea.

Named Kim Ki-Jong, he’s a 55-year-old who leads a leftist political organization called Urimadang — or Our Square — that protests Japan’s territorial claims over some South Korean eastern islands and opposes military exercises conducted by foreign forces in South Korea. According to reports, he made clear his political motives for the attack in the chaotic aftermath as the bloodied ambassador was taken to a hospital where he received 80 stitches.

“I carried out the terror attack,” said Kim, who broke his ankle during the attack, according to the Korea Herald. “I have prepared to disseminate leaflets to oppose the [South Korea-U.S.] military exercise for a war.” The leaflet asked for the “suspension of the exercise that blocks inter-Korean dialogue and Seoul’s retaking of wartime operational control [from Washington].” He added: “I oppose the military drills, a reason why the two Koreas can’t hold the reunions of separated families.”

The attack was 10 days in the making, he said. He claimed he acted alone. “I made a sacrifice myself so as to stop the Key Resolve exercise,” referencing an annual joint-training event held by U.S. and South Korean forces. He said, according to the Yonhap News Agency: “I [attacked the ambassador] because I don’t like how a moron who’s barely in his 40s was going to take on our inter-Korean policy.”

This was far from Kim’s first act. The activist, who led a Seoul-based group dedicated to unification, reportedly tried to self-immolate with gasoline in 2007 when protesting in front of the presidential Blue House. According to reports, he wanted the government to look into an alleged rape that happened in his office in 1988.

An undated picture shows Kim Ki-jong at a rally in front of the U.S. Embassy in Seoul. (Yonhap via European Pressphoto Agency)

Then in 2010, he was behind an attack on a foreign ambassador when he threw pieces of concrete at Japanese envoy Toshinori Shigeie. At the time, the Korea Joongang Daily reported that, during a question-and-answer session featuring the Japanese diplomat, Kim became very agitated. He blamed the divided Korea on Japan and, screaming, pulled a piece of concrete from a paper bag. Then he hurled it at the ambassador and missed. Instead, he struck the ambassador’s translator, who was taken to the hospital.

For the attack, he got two years in prison and three years of probation. Months after he got out of prison, Kim, who intelligence officials said traveled to North Korea numerous times to plant trees, constructed in downtown Seoul a “memorial altar” for North Korean leader Kim Jong Il, who had just died.

Meanwhile, he tended to his blog. He recently became more obsessed with the close relationship between South Korea and the United States, Yonhap reported. On Tuesday, the day before the attack, he criticized joint military drills. He condemned them as “the reasons why the reunion between family members [separated by the 1950-53 Korean War] couldn’t take place.”

Police are plotting a raid on his house and mulling whether to charge Kim with attempted murder.