South Korea, Dec. 7 -- To hear a beaming Donald Trump at his June summit with Kim Jong Un in Singapore, the solution to North Korea's headlong pursuit of nuclear weapons, a foreign policy nightmare that has flummoxed U.S. leaders since the early 1990s, was at hand.

Since the remarkable claims made during the first-ever meeting of leaders from the archrival nations, however, there have been recriminations, simmering bad blood - and very little progress. In other words, just what skeptics in Seoul and Washington have come to expect from North Korean nuclear diplomacy.

So even as Trump says he's keen on another summit, possibly early next year, continuing sanctions and pressure from Washington are met with anger and foot-dragging from Pyon...