The good news from Pyongyang is that North Korea’s dictator says he still wants to give up his nuclear weapons. But Kim Jong Un’s summit Wednesday with South Korean President Moon Jae-in, the third this year, brought no significant progress toward that goal, notwithstanding the bonhomie.

Kim did pledge to dismantle a missile-test range, but he told Donald Trump the same thing in Singapore in June. This time, though, he will allow international experts to watch. The North Koreans are experts at selling the same horse twice,...