Summits are tricky: Presidents Kennedy, Nixon and Reagan learned the hard way,

WASHINGTON—In his 1961 inaugural address, President John F. Kennedy spoke about the possibility of daring diplomacy to thaw even the coldest of relationships: "Let us never negotiate out of fear. But let us never fear to negotiate."

Those words, often cited by President Barack Obama, could also be repurposed by President Donald Trump—if the 45th president were into quotations—as he embarks on the highest-stakes U.S. summit in a generation, sitting down in Singapore Tuesday with Korean dictator Kim Jong Un.

But Kennedy's most consequential summit, which came just months into his presidency, was an unmitigated disaster, according to historians.

Despite careful preparation, the young president did not heed the warnings of advisers familiar with his Soviet counterpart, Nikita Khrushchev, whom he met in Vienna in June 1961. Kennedy's attempts to establish a friendly rapport, which experts had cautioned him against, came across as weakness.

After the summit, he knew immediately he'd blown it, as did William Lloyd Stearman, a national security aide who traveled with Kennedy to Vienna.

"It was Al Capone meets Little Boy Blue," Stearman said last week. "Kennedy was not used to dealing with a thug like Khrushchev. And the Cuban missile crisis can be traced back to Khrushchev's feeling that Kennedy was weak."

Historians generally share that conclusion. Their understanding of that and other consequential summits, like President Richard Nixon's 1972 trip to China and the meeting between President Ronald Reagan and Russia's Mikhail Gorbachev in 1986, especially worries them about grave risks of Trump's brash, media-centric diplomacy as he comes face-to-face with Kim.

Although he often criticizes his predecessors for failing to resolve the nuclear stalemate on the Korean peninsula, Trump seems largely indifferent to history and its lessons. According to a recent report, he asked Canada's prime minister about his country's military setting fire to the White House during the War of 1812 (it was British troops who did that).

Trump is heading into the Singapore summit, an effort to stave off a nuclear-armed North Korea, with his characteristic nonchalance, saying that his lack of traditional preparation— National Security Council meetings, of which there have been none, thick briefing books and hours of Situation Room strategizing— be more than offset by his instincts and "attitude."

"This is a neophyte who has given every indication that he does not like to do his homework, and the cost could end up being very great," said presidential historian Michael Beschloss. "We've never seen a president who wears as such a badge of honor that he won't prepare. There's no president in American history that has done that, and certainly not on a summit as important as this.

"For Americans, the lives of their children are literally depending on what is said. He is the guardian of every American life. How seriously does he take that responsibility?"

It's been less than a year since Trump threatened to "annihilate" Kim, whom he called "Rocket Man." He has since softened his words, but he believes his bellicose rhetoric, amplified on Twitter, had a significant role in getting North Korea to suggest face-to-face talks.

Those comments reminded some of the so-called "madman theory" that was later ascribed to Nixon and his envoys' attempts in 1969 to convince the Russians that the U.S. president was unhinged and capable of doing anything to resolve the stalemate in Vietnam.

"Given his admiration for Nixon, Trump could be using it as a model," said John A. Farrell, author of "Richard Nixon: A Life," published last year.

But Nixon's efforts to scare Russia did not bear fruit. What did work was his 1972 visit to China, which restored a diplomatic relationship between the two world powers. That triumph occurred only after years of diplomatic spadework, including a secret visit Henry. Kissinger to China a year earlier.

Nixon benefitted from having Kissinger by his side and from having spent years immersed in U.S. foreign policy regarding the Soviet Union. The Shanghai Communique that resulted from the summit, in which the U.S. begrudgingly accepted the One China policy under which Taiwan was considered a part of China, was a simple, narrow agreement that arose out of a confluence of mutual interests and laid the foundation for future talks.

Nixon, Beschloss said, "had done this for decades and was a careful student of history. One of the important tools that a president's got in a negotiation like this is to know what's worked and what has not. I just don't know how a president can feel he's defending American security without having that kind of background."

Trump, who is relying primarily on Secretary of State Mike Pompeo, agreed hastily to the summit with Kim in March almost as soon as South Korea informed him that the North Korean leader sought a meeting. In the three months since, Pompeo has twice met with Kim to discuss denuclearization, setting the table for the complex negotiations in Singapore.

"Nixon was very quiet personally in these situations, more careful and more shy," said Julian Zelizer, a historian at Princeton University. "Trump's the opposite: He's more explosive and liable to say anything."

Like Nixon, who went to China without knowing if Mao Zedong would greet him, Trump is accepting some political risk in meeting with Kim, who is unlikely to scrap the nuclear program that brought the U.S. to the negotiating table without securing major concessions— much heavier lift than Nixon had in 1972.

"Nixon had no preconditions going in, and both countries came out of that summit with nothing other than the understanding that they needed to talk and coexist," said Timothy Naftali, a presidential historian at New York University. "The (1972) summit's achievement is just in the fact that it happened."

Trump, who has toggled between unbridled optimism with effusive praise for Kim and bluster that he may abruptly walk out of their meeting if it goes poorly, has only recently engaged in setting more modest expectations for the summit, saying that this meeting could be just the beginning of a continuing dialogue.

"I'm not sure if he'll recognize that a good, constructive meeting can be a victory in itself," Naftali continued. "If he's not careful, he could paint himself into a corner, seeking an achievement he can't actually get. That's what Kennedy did with Khrushchev."

Like the Singapore summit, Ronald Reagan's 1986 summit with Gorbachev in Reykjavik, Iceland, was hastily arranged in response to Gorbachev's sudden willingness to ban all ballistic missiles. Reagan engaged in remarkably free-form negotiations and nearly came to a far-reaching agreement. But Reagan ultimately balked, unwilling to give up his "Star Wars" missile defense program.

What at the time appeared to be a diplomatic failure is now seen as a success, as the talks allowed both countries to realize their shared desire to avoid a war and better understand the concessions each was willing to make. The next year, the U.S. and Soviet Union agreed on an arms reduction treaty. Now, historians view the meeting in Reykjavik as the beginning of the end of the Cold War and the Soviet Union itself.

"Reagan's command of detail was not great, but we know now that he had actually been studying these issues for decades," Beschloss said. "He had a very specific idea of how the Cold War would end. This was not a neophyte stumbling into the room."

The Singapore summit will be different. It is the first major summit to occur in the social media era and the first involving two leaders as unpredictable and untested as Donald John Trump and Kim Jong Un.

For the past year, Twitter has enabled Trump and Kim to speak to each other directly without the filters of experts and aides—and that dialogue has taken a number of twists and turns. But it has also led to Singapore and a summit that historians, for all their concerns, are hoping will yield something positive. Although forming a clear-eyed and lasting assessment of its success or failure could take years, there is a possibility for success.

"Experts on diplomacy scoff at this, but the proof of whether a summit is successful or not is the result," Farrell said.