In 1996 on September 15, a North Korean landed a three-person special operations reconnaissance team on the east coast of South Korea near Jeongdongjin, south-east of Gangneung, Gangwon-do. Their mission was to spy on the naval installations in the area and then return. The submarine made a failed attempt to collect the team on the 16th and returned the following day. It ran aground in the attempt, and all efforts to free her were unsuccessful. The crew then decided to destroy the sensitive equipment in the submarine and try to make it to the DMZ. The crew split up in several groups but one was soon spotted by a civilian who became suspicious and alerted the authorities, who quickly mobilized.
A 49-day-long manhunt ensued, from 18 September through 5 November, resulting in the capture or elimination of all the crew and members of the reconnaissance team, except one, who is believed to have made it back to North Korea. Four civilians and 12 South Korean soldiers died; 27 soldiers were wounded. Of the 25 North Korean infiltrators, one was captured, 11 were killed by the other members for failure in responsibility of running aground of the submarine, and 13 were killed in firefights with the South Korean army. Some analysts suspected that the motivation behind the assassination of Choe Deok-geun, South Korean consul for the Russian Far East, was North Korean retaliation for the loss of their men. The infiltrators possessed among their arsenal M16A1 rifles and imitation South Korean-style military uniforms. Nestlé Crunchchocolate bars were also recovered. Some of the dead spies' corpses were displayed to the media; some were wearing South Korean-style military uniforms as disguises. The submarine was salvaged and towed to a naval base for investigation. The sole captured crewmember, the submarine's helmsman, Lee Kwang Soo, gave in after much interrogation and revealed much of the plans. He later became an instructor in the South Korean Navy. North Korea was at first reluctant to take responsibility, claiming that the submarine had suffered an engine failure and had drifted aground. By 29 December, however, the North issued an official statement expressing "deep regret" over the submarine incident. In return, the South Korean government returned the cremated remains of the infiltrators to the North via Panmunjom on 30 December.
Timeline of North Korean casualties
September 18, 16:40 – 1 captured by local policemen
September 18, 17:00 – 11 bodies of executed submarine crew members were found
September 19, 10:00 – 3 killed by the South Korean army commandos
September 19, 14:00 – 3 killed by the South Korean army special forces
September 19, 16:00 – 1 killed by the South Korean army
September 21, 20:00 – 1 killed by the South Korean army
September 22, 06:00 – 1 killed by the South Korean army
September 28, 06:30 – 1 killed by the South Korean army