An arms control expert says U.S. President Donald Trump pulled the plug on a historic North Korea summit because he's a "fool" who only wanted the meeting "for the basest of reasons."

In a formal letter addressed to North Korean Leader Kim Jong-un, Trump wrote, "Sadly, based on the tremendous anger and open hostility displayed in your most recent statement, I feel it is inappropriate, at this time, to have this long-planned meeting."

The letter came hours after North Korea claimed to have destroyed its nuclear test site.

Jeffrey Lewis, an arms control expert from the Middlebury Institute of International Studies, spoke to As It Happens host Carol Off about what he makes of the president's abrupt decision to cancel the face-to-face summit.

Who is to blame for this falling apart?

This entire crisis began because [National Security Advisor] John Bolton insisted on repeatedly publicly referring to the Trump administration's expectation that it would get what Bolton called a "Libya-style deal."

This was a preposterous comparison. Libya had really no nuclear weapons program to speak of. It had just some technologies it had imported, but really had no prospect of ever completing it.

But Bolton was really raising it not because of disarmament, but because of how [former Libyan leader Moammar] Gadhafi died.

I think Bolton wanted to sabotage the summit.

This is from the letter again: "Your tremendous anger and open hostility displayed in your most recent statements has meant the cancellation of this." Can you tell us what those statements were?

Those were statements by two senior North Korean officials. The first statement by [arms negotiator] Kim Kye Gwan, it really focused on Bolton and Bolton's Libya comments.

And to some extent, the White House responded positively to that. Sarah Huckabee Sanders said that it wouldn't be a Libya-style deal, it would be a Trump-style deal.

But then the second North Korean official came out and she, I think, really offered the statement that was the straw that broke the camel's back.

What she said was that it was the U.S. who had asked for the meeting. And I think that a lot of this has been driven by the president's ego — that is the thing that he identifies at the top of the letter.

He says it's irrelevant but, it's the first thing he talks about — the idea of who invited whom. I think for Trump it was very important to depict this as the North Koreans coming to him because they had been pressured.

And I think for the North Koreans, it was the opposite narrative, that Trump was coming to them. So, it turns out Singapore is not big enough for both their egos.

Sadly, I was forced to cancel the Summit Meeting in Singapore with Kim Jong Un. <a href="https://t.co/rLwXxBxFKx">pic.twitter.com/rLwXxBxFKx</a> —@realDonaldTrump

But President Trump was basking in this idea that he was going to not only be the first one to have this kind of a summit with North Korea, but that he would win the Nobel Peace Prize for it. So did he not see this coming?

This is always a difficult thing in an interview because it comes off as partisan, but the president is a fool. He is a real fool.

Ask anyone who actually dealt with him in business. He is not a person who is aware of policies, ideologies. He is an ego-driven person.

And so, for him, the details are not something that interest him or that he would have any capacity to deal with. I know it seems hard to believe, but the president is a fool.

He wanted the meeting for the basest of reasons and that's why it got as far as it did.

Lewis says the summit was driven by Trump's ego more than a desire for disarmament. (Omer Messinger/Getty Images)

Do you think this letter is an attempt to try to and get it back on the track that he wants it to be on?

Yeah, Wendy Sherman, who had served in the Obama administration, I think aptly summarized it as, "a 13-year-old's stream of consciousness in a breakup letter over summer camp."

And it does have that strange sexual harassing quality of denigrating Kim, but at the same time asking him to come back.

I think what we are dealing with is not really a policy dispute but a man's bruised ego. He wants to have the summit, but he wants to have the summit in a way that makes him feel good about himself.

Wendy Sherman wins the award for best quote today:<br>"13-year-old stream of consciousness in a break-up letter over summer camp." <a href="https://t.co/pOGzjVA3G1">https://t.co/pOGzjVA3G1</a> —@ArmsControlWonk

A colleague of ours, [Toronto Star reporter] Daniel Dale, asked you for a comment on Twitter. You described it as a "goat rodeo." What did you mean by that?

A rodeo is a show and it has some drama to it. But if you replace the horses with goats, all that drama is replaced with humour and what you're left with is a farce.

And that's what this was. This was a farce.

It had the appearance of a diplomatic process, but it had none of the substance.

Transcript of my exclusive interview with <a href="https://twitter.com/ArmsControlWonk?ref_src=twsrc%5Etfw">@ArmsControlWonk</a> <a href="https://t.co/OtZSo7MrV5">pic.twitter.com/OtZSo7MrV5</a> —@ddale8

Even if there had been a summit, or I guess if it still happens, do you think it actually would have led to North Korea denuclearizing its —

[Laughter] No.

Written by Jeanne Armstrong and John McGill. Interview produced by Jeanne Armstrong. Q&A has been edited for length and clarity.