Silmido 실미도 Korean Movie eng hard sub
Release Date: December 24, 2003
Runtime: 135 min. 
http://asianwiki.com/Silmido 
https://www.imdb.com/title/tt0387596/

Based on a true story of 1968 Korean Republic Army plan to assassinate North Korean president Kim Il-Sung. 31 criminals and death row inmates are recruited into secret training on the island of Silmi; for two years they are subjected to maximum mental and physical abuse before the mission is cancelled and the unit terminated