South Korean conservatives have had two nightmare scenarios about President Trump: that he would either embroil their country in a ruinous war with North Korea or that he would sell out their interests to the North.

Trump spent his first year in office lending credence to the first concern. He threatened to rain “fire and fury” down on North Korea. He called its dictator, Kim Jong Un, “Little Rocket Man,” and bragged that his “nuclear button” was much bigger than Kim’s. Administration officials claimed that deterrence couldn’t work and discussed the possibility of a “bloody nose” strike that could have triggered a nuclear war.

Now, in a head-snapping display of incoherence, Trump has agreed to meet Kim, giving the worst human-rights abuser on the planet what he most wants: international legitimacy. Kim will be able to tell his people that the American president is kowtowing to him because he is scared of North Korea’s mighty nuclear arsenal.

As recently as August, Trump tweeted: “The U.S. has been talking to North Korea, and paying them extortion money, for 25 years. Talking is not the answer!” He was absolutely right. For decades, North Korea has engaged in a bait-and-switch. It has staged provocations, such as the torpedoing of a South Korean naval ship in 2010, interspersed with offers to negotiate. The end game has always been the same: It has hoped to be paid for not staging further provocations. In other words, it was attempting to blackmail the West.

That strategy paid off spectacularly during the “sunshine policy” years of 1998 to 2008. Progressive governments in Seoul delivered approximately $8 billion in economic assistance and got nothing in return. North Korea reneged on its 1994 pledge to the United States to freeze its nuclear development and instead raced ahead with a secret nuclear enrichment program. South Korea’s current president, Moon Jae-in, was a top aide to President Roh Moo-hyun, one of the presidents who pursued the sunshine policy, and evidently he has not lost his faith in negotiations with the North. Admittedly, from his perspective, it makes sense to do anything possible to stop Trump from starting Korean War 2.  

Moon and Kim have, for their own reasons, snookered the credulous American president into a high-profile summit that is likely to end in disaster one way or another. Kim is evidently willing to suspend his nuclear and missile tests while the talks are underway, but this is a minimal concession that can easily be reversed. He is most likely willing to do even that much only to buy time for his engineers to finish developing a nuclear warhead that can fit on an intercontinental ballistic missile capable of reaching the United States....