Assume the coup fails. How does South Korea purge its military of coup participants without significantly reducing its readiness for conflict with a resurgent north Korea?
It sounds like the military has been obeying the President’s orders somewhat halfheartedly, in a manner which has deprived them of much of their effectiveness. I’m not sure in that scenario it is right to label them as “coup participants”.
It's not clear anyone in the military participated beyond pretending to follow orders. Soldiers guarding the National Assembly seemed to do a terrible job securing the building and it may have been intentional. A reporter on the scene reported that soldiers were scared when an Assemblyman yelled at them.