In "Cranes," what is the real reason that Songsam unties Tokchae?

You need to analyse the role of the flashback which we are
told about just before the end of the story. In this flashback, we are persented with
the two men as children, and how they together caught a crane, and then realised that
its freedom was worth more than anything. Consider how this release of the crane is
described:

But
the next moment, as another crane from a nearby bush fluttered its wings, the boys'
crane stretched its long neck with a whoop and disappeared into the sky. For a long time
the two boys could not take their eyes away from the blue sky into which their crane had
soared.

Clearly the way in
which the boys are mesmerised by the blue sky shows the way that they value freedom more
than capture. The decision of Songsam to therefore let his friend escape and enjoy the
same freedom indicates their understanding that freedom is infinitely more important
than capture, and also symbolises how the strength of friendship can overcome the power
of competing ideologies.