President Trump’s plan to meet Kim Jong Un has already had one effect — it has flipped the New York Times. Only a few months ago the Times was complaining that Mr. Trump had threatened at the United Nations to destroy totally North Korea, while offering “hardly a hint of compromise or interest in negotiations.” Now the Gray Lady is rushing out an editorial saying that for once, Mr. Trump is doing the right thing, though of the editorial is devoted to sneering at the president.

The Times’ star columnist, Nick Kristof, reckons the summit is a “dangerous gamble and a bad idea.” They both fear that the President is not up to the task. We’re for diplomacy only as a last resort. Diplomacy’s danger is that it could hold out to the North Koreans the hope of a peaceful outcome and the possibility of permanent recognition of the jackbooted Juchists. It was a danger that was once descried — and decried — by liberal anti-communists, most eloquently by the Jewish Daily Forward.

On the morrow of the Communist assault on South Korea in June 1950, the Forward had issued a famous editorial warning of “the swindle and hypocrisy of the so-called ‘Peace Campaign’ which Moscow’s agents have been promoting throughout the world.” It made it clear that it comprehended that absent a retreat by the communists a new world war would become inevitable. That world war sputtered between hot and cold for two generations.

America’s own sacrifices in that war were enormous, not that the sacrifices of our allies were any less, and Korea is one of the last battles. This is the burden Mr. Trump will carry to any Korean summit. Secretary of State Tillerson is cautioning that what’s ahead are mere talks, rather than proper negotiations. He did not define the difference, the AP reported, noting that our two countries are “still technically at war.” If that’s true, why are we even talking?

The moment reminds us of, say, the closing days of our own civil war. There was a danger of a peace being negotiated in the last days of a war in which the Confederacy had already been defeated. (The crisis is dramatized in the movie “Lincoln.”) In the case of Korea, Mr. Trump is hobbled by a South Korean administration that came into office campaigning for appeasement and a federation with the North. The hardline president who would have known better is now sitting in a prison cell.

Our own skepticism of outreach to the North goes back years. In the late 1970s, we sat with Kim Dae-jung, then a dissident politician, in the parlor of his home in Seoul. He was under house arrest at the time. He was pressing his own vision for outreach to the North. We doubted he was up to it. “No democracy, not strong,” he kept telling us. In one of those astounding events for which Korea is famous, he ended up as president.

Once in the Blue House, Kim Dae-jung pardoned, in Chun Doo Hwan, the president who’d once sentenced Kim to death. Kim Dae-jung also launched his so-called Sunshine policy and made a visit to the North. He won the Nobel Prize for Peace in 2000. It all ended in scandal and recrimination, though, when it turned out that the Sunshine summit had been purchased with hundreds of millions of dollars of transfers to the regime Kim Jong Un’s father headed. The deal, it seems, turned out to have been artless.