One of the stranger missions to come about during World War II was the decision to infiltrate the Korean coastline, which was then held by the Japanese, and insert former Korean POWs into the country to set up agent networks, conduct sabotage and possibly begin a guerrilla war against the Japanese. Eventually, the plan was to infiltrate the coastline of Japan itself.
Code-named Operation NAPKO, it was headed by the Office of Strategic Services (OSS), the forerunner to both CIA and the U.S. Army Special Forces. Operation NAPKO was run by Colonel Carl Eifler, the larger-than-life OSS operator, who was the first commander of Detachment 101 in Burma that recruited and trained the Kachin Rangers.
The plan was to use a semi-submersible boat, code-named the GIMIK, to shuttle 10 teams (each comprised from one to five personnel) of Koreans onto the coastline where they would use their own contacts to set up agent networks. The former POWs would choose their own infiltration points due to their personal knowledge of the operational areas. The agents would then set up radio communications with U.S. listening posts in Manchuria and the Philippines.
The 55 Koreans selected for the mission were given extensive training by OSS and each of the teams were kept separate and unknown to each other. That way, in case of capture, they wouldn’t be able to relay anything of importance to the Japanese.