Trump was right to call off a meeting that could have been a debacle.

Donald Trump described his decision Thursday to nix his June summit with North Korean dictator Kim Jong Un as a “tremendous setback” for North Korea and the world, but the better word might be relief. Mr. Trump had overestimated Kim’s willingness to give up his nuclear weapons and was heading toward a summit failure.

Mr. Trump agreed to the summit in part because South Korean President Moon Jae-in misrepresented the North’s position after talks with Kim’s sister at the Winter Olympics. After claiming Kim had a change of heart about nuclear weapons, Mr. Moon pursued his plan to resurrect the Sunshine Policy of appeasement toward the North that failed in the 2000s.

This created a peace euphoria in the South that pushed the Trump Administration to explore the opening to preserve the alliance.

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