In the short story, Cranes by Hwang Sun-won, Song-sam did not first intend to release his prisoner Tok-chae. This story is a metaphor of South and North Korea's relationship amidst its most recent division into North and South jurisdictions by the United States and Russia following the surrender of the Japanese and the end of World War II in 1945, and it's more entrenched division solidified during the subsequent Korean War (1950-1953). Song-sam represents South Koreans and Tok-chae represents North Koreans, who were once family and friends, however, now are sworn enemies due to their allegiances during the Korean War.
When Song-sam was ordered to detain Tok-chae, he saw his old childhood friend as a communist who had been radicalized by the prevailing ideology, however, after hearing of Tok-chae's reasons for not leaving North Korea (he had to stay and help his father on the farm) and also hearing about Tok-chae's wife, Tok-chae began to take on a more human form in Song-sam's eyes. To Song-sam, Tok-chae was no longer a radicalized communist, he was a childhood friend. And for this reason, Song-sam decided to release Tok-chae.
Cranes are sacred birds to Koreans and represent their connection to the Korean land. The imagery of two cranes flying off at the end is a representation of eventual unification of North and South Korea.
