I am writing this on my way back from Pyongyang where I was on a mission to promote language studies.No one should suspect that I am North Korea apologist. But after 40-odd years of experience in Korean affairs I feel I can make some conclusions, especially concerning the burning issue: how to stop North Korean nuclear potential's increase in the wake of the fifth nuclear test, and what immediate measures should be taken by the international community?This issue becomes more urgent day after day, as the continued unchecked increase in Pyongyang's nuclear and missile capabilities is almost certain