It just hit me as I was looking at KE's route map, why wouldn't or why couldn't they set up pre-clearance at ICN? Would it not be beneficial or are there regulations preventing such a pre-clearance being set up? Or maybe it has to do with the frequency of flights that are operated airlines... for instance ICN, or NRT/HND etc, do not have as many flights as say YYZ or YVR to the US?
I do understand that there are plans to set up a pre-clearance in PUJ.
Anyway I thought it would be an interesting topic to bring up.