Donald Trump's big fail on North Korea: He didn't prepare and he got played Kim Jong Un is a ruthless butcher. For Donald Trump to claim North Koreans love him shows how badly he misjudged Kim or just wanted a 'deal.' Any deal.

Paul Brandus | Opinion columnist

Show Caption Hide Caption Trump's bizarre Hollywood-style video to Kim Jong Un, explained The Hollywood-style video that President Trump showed Kim Jong Un is a bit of a head-scratcher, but it actually makes sense. The underlying imagery and symbolism tell a far greater story. We explain.

Here’s how hyperpartisan our bizarro world has become: Many of the same folks who, a few years ago, blasted President Obama for going to Cuba and for working with other global powers to rein in Iran’s nuclear program, are gushing over the fact that President Trump just flew 10,000 miles to meet with Kim Jong Un. Conversely, if you praised Obama’s actions then, there’s a good chance you've been critical of Trump’s now.

Let’s be honest. A 55-year economic embargo against Cuba didn’t change Cuba. Our deep freeze against Iran, in place for 40 years, hasn't changed Iran. Two-thirds of a century after the Korean War ended, nothing has changed there, either. The Kim dynasty has smoothly transitioned from father to son to grandson.

So what’s wrong with either Obama or Trump trying to end decades of failed policies in these places? If a U.S. president thinks he can effect change in Havana, Tehran or Pyongyang, I think he should try, and I think Americans should put aside their knee-jerk partisanship and wish that president well. America has turned enemies into friends before — Britain, Germany, Japan, Vietnam — and one day, and as implausible as it seems today, perhaps we can do so again.

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In this light, though I've been a harsh Trump critic for years, I think the president deserves credit for trying to do something about North Korea. It has been a thorn in our side since Harry Truman was president — and that was a dozen presidents ago.

Trump haters say the only reason he's making the effort with North Korea is because Obama told him it would be his biggest problem. Who cares? Let him try.

Still, I’m compelled to wheel out a habitual complaint about Trump: Namely, that he’s too casual and lacks a fundamental understanding of critical issues. Nor is he interested in learning about them.

Case in point: The most revealing thing Trump said Tuesday wasn’t during his hour-long news conference in Singapore — just his second, full-blown session with reporters since taking office. It was what the president said immediately afterwards, when he sat down for an interview with ABC News’ George Stephanopoulos.

Asked about Kim, whom Trump had just met for several hours, the president said, “His country does love him. His people, you see the fervor. They have a great fervor.”

Love? Fervor? North Korea is a living hell, infamous for executions, torture and mass starvation. North Koreans don't love Kim. They hate and fear him, and risk their lives to escape his murderous grip. For Trump to claim that Kim, a ruthless butcher of his own people, is loved tells me either how badly he has misjudged Kim, or how badly he wanted to leave Singapore with a “deal.” Both scenarios left Trump vulnerable to manipulation, and that's what happened –– he was manipulated by a man half his age.

Trump wanted to leave Singapore with a piece of paper showing what he had accomplished. Here’s what was accomplished: He agreed to meet Kim (an “honorable man”) with no preconditions. He avoided any discussion on human rights. He agreed to end U.S. military exercises — saying they were provocative and cost too much. The president also expressed a desire to pull American troops from South Korea. Both of these concessions appear to have been made without consulting South Korea itself, and in return, Kim gave up nothing to get them.

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Even so, all of this might have been worth it if Trump had been able to pin down Kim on the one key demand Trump has been talking about for months: denuclearization. But the joint statement they issued says nothing about any "complete," "verifiable" or "irreversible" denuclearization — only a flimsy line that they’ll work on the issue. This kind of wishy-washy vagueness is a big fail.

The statement also said nothing about North Korea’s deadly arsenal of chemical and biological weapons. U.S. officials believe that North Korea's chemical weapons have been given to Bashar Assad's murderous Syrian regime and dropped on Syrian civilians. For these deadly weapons to be omitted from the Singapore communiqué is another big fail.

Trump also bragged about how he didn’t really prepare for Tuesday’s historic sit-down. He didn’t have to, he said, because his gut instinct about people is always good and he would get a feel for Kim within the first minute. If the president can’t be bothered to prepare for a meeting that could help prevent nuclear war, than there’s nothing he’ll prepare for. This is an ad-libbed, improvisational presidency where the gravest issues are dealt with almost cavalierly.

That’s where Trump deserves criticism. Not that he wants to do something about a problem that has bedeviled the past dozen presidents — but that he’s so damn flip and casual about it.

Paul Brandus, founder and White House bureau chief of West Wing Reports, is the author of Under This Roof: The White House and the Presidency and a member of USA TODAY's Board of Contributors. Follow him on Twitter: @WestWingReport.