( CNN ) The suspect behind the knife attack on the American ambassador to South Korea had a long , troubled history and often blamed the U.S. for tensions in the Korean Peninsula . Kim Ki-Jong , 55 , was quickly overpowered and taken into custody after he attacked U.S . Ambassador Mark Lippert with a fruit knife Thursday morning . Police say Kim 's motive for the attack was to improve North-South Korean relations and to stop the annual military exercises held jointly by the U.S. and South Korea . It was n't the first time Kim has taken drastic steps to make his point . -- In 2010 , Kim was given a suspended jail sentence for hurling a concrete block at a Japanese envoy to South Korea , according to the Yonhap news agency . That incident is believed to be the first attack on a foreign ambassador in South Korea . -- Kim allegedly harbored sympathies for North Korea , according to Korean media reports . Yonhap reported that Kim had visited North Korea six times between 2006 and 2007 , had attempted to erect a memorial for former North Korean leader , Kim Jong-il in Seoul , and once set himself on fire in front of the presidential office . -- He was frequently seen at protests , wearing a beret and blaming U.S. policies for straining relations between North and South Korea . Kim was a member of the Korea Council For Reconciliation and Cooperation , which hosted Lippert at the Thursday event where the attack occurred . The group advocates reunification of the Koreas as well as humanitarian aid to North Korea . Kim was one of its 181 members , but was n't on the list of those invited for the event , according to police . But he was allowed in because an event staff recognized him from the organization . A witness who was sitting next to Lippert during the attack said Kim was known for having `` unpredictable behavior '' in the organization . Even though he appeared somewhat disheveled Thursday morning , he was able to enter the event because the staff was familiar with Kim , police said . Immediately after he allegedly slashed the ambassador in the face and arm , Kim was tackled to the floor . As he was transferred to a hospital Kim shouted , `` The South Korea-U.S. military drills must stop . '' Every year , the United States and South Korea hold joint military drills , which both countries say are defensive and non-provocative in nature . But the exercises also draw criticism from the North Korean regime , which characterize the drills as rehearsals for an attack on the regime . Kim also told South Korean reporters that he had planned the attack for 10 days , and claimed responsibility for burning a U.S. flag at the embassy in the 1980s . A website associated with Kim , displayed a photo of him with protesters holding a sign that read : `` Stop war exercises that block North-South Korean dialogue . '' The picture was taken at February 24 , in front of the U.S. embassy , according to his website . It also contains a picture of an American soldier inside a red crossed-out circle . On Thursday , Kim shouted at reporters , saying that the U.S. was to blame for blocking family reunions of North and South Koreans who have been separated since the Korean War . On the website , he lamented that `` the whole atmosphere of the Korean peninsula is freezing up like a frozen soil . '' CNN 's KJ Kwon and Paula Hancocks in Seoul contributed to this report , as did CNN 's Judy Kwon and Sol Han from Hong Kong .
Suspect Kim Ki-jung was captured after North Korea ambassador was slashed in Seoul . Kim had history of anti-North Korea sentiment and sympathies for U.S. .