Accroding to wikipedia, he was in South Korean Special Forces at the time. Here's what the wikipedia article about the south korean special forces involvement in the Korean axe murder incident

> In addition, a 64-man task force of the South Korean Special Forces accompanied them, armed with clubs and trained in taekwondo, supposedly without firearms. However, once they parked their trucks near the Bridge of No Return, they started throwing out the sandbags that lined the truck bottoms, and handing out M16 rifles and M79 grenade launchers that had been concealed below.[3] Several of the commandos also had M18 Claymore mines strapped to their chests with the firing mechanism in their hands, and were shouting at the North Koreans to cross the bridge.[12][13]