When dealing with the Kim Jong Un conundrum, watch out for premature Yoko Ono-like “war is over” declarations.

False diplomatic progress is an underappreciated obstacle. Like belligerent threats, it, too, can lead to disaster. So, are our diplomats pushing too hard when they should be tapping the breaks?

President Moon Jae In of South Korea is leading the forward charge. He’s planning a third Pyongyang summit with Mr. Kim in September. On Wednesday, he announced plans for joint-economic zones and expressed a desire to connect the Koreas by rail line. Reunification, anyone?

Also, Mr. Moon “unofficially” sent a message to Washington this week, an unnamed Seoul official told the Korea Times: Next month, as world leaders gather for their annual United Nations gabfest, he hopes to sign a pact to “end the war with North Korea and China.”

America may be skeptical, the Seoul official cautioned, but a “roadmap” to Pyongyang’s denuclearization could get Washington on board.

Maybe. Secretary of State Pompeo will visit Pyongyang for the fourth time in August. “The US and the #ROK remain in close cooperation to ensure the final, fully verified denuclearization of the #DPRK. We believe progress can be made,” he tweeted Tuesday.

Not to be left out, China’s president, Xi Jinping, reportedly plans a Pyongyang visit as well. At the United Nations, Russian diplomats are pushing for formal easing of Security Council sanctions on North Korea. With the exception of China, the other council members are unlikely to bite. But that’s almost beside the point: Sanctions violations are already rampant.

So are we there yet? Is war over?

Remember President Trump’s June tweet? That “President Obama said that North Korea was our biggest and most dangerous problem. No longer — sleep well tonight!”

A good night’s sleep is healthy, but the NoKo nightmare’s still here — and Seoul’s dreamy diplomacy can make things worse.

Mr. Moon’s a big believer in the theory that once exposed to the world, and with an improved economy, the North will mellow out. The Clinton-era Sunshine Policy is his Moonshine.

For some of his top advisers, the presence American troops on the 38th parallel is a bigger threat than the cruel dictatorship to its north. If they overcome domestic defenders of the old ways, Seoul may abrogate our mutual-defense treaty and give the Yankee troops a year to pack up.

All music to Mr. Kim’s ears. He’d love to replace the 1953 ceasefire agreement with a formal treaty that’d immediately force American troops out of the peninsula.

And then what? Even more than his father and grandfather, the 33-year-old Mr. Kim is surrounded by yes-men. “None of his advisers are professional, military advisers, they’re all political appointees,” says Colonel David Maxwell, who’s now retired but served five tours in Korea.

If these advisers are asked, says Colonel Maxwell, now a keen Korea watcher at the Foundation for Defense of Democracies, they’d probably tell Mr. Kim that his mighty army can win a war against the South after an American withdrawal.

Yes, Mr. Trump is eager for a legacy-building diplomatic victory. As the November elections approach, politics will add pressure to show progress on North Korea, even if none exists. But beware premature end-of-war declarations.

Pyongyang “will remain a nuclear threat until they disarmed all their nuclear weapons,” a Security Council diplomat said Wednesday, adding that sanctions shouldn’t be eased until then.

True: Mr. Trump’s early threats, and then the Singapore summit thaw, resulted in a lull as North Korea ceased launching long-range ICBMs. Also, Pyongyang partially dismantled facilities and returned the remains of several Korean War-era MIAs.

Yet, to date the North hasn’t “taken the steps we feel are necessary to denuclearize,” National Security Adviser John Bolton told Fox News.

That’s really all that matters. On Wednesday the Treasury Department listed new Russian and Chinese firms that’ve violated North Korea sanctions. The administration’s Korea hawks, it seems, are so far holding the line.

This column first appeared in the New York Post.

Yet South Korea, China and others are whispering in Trump’s ear that appeasement will soon bring peace.

It won’t. Trump’s predecessors eagerly fell for false promises, which is how we got here.