Hanoi, Vietnam (CNN) It was meant as the sequel to rival the original -- another far-flung encounter, laced with backslapping and friendly banter alongside the world's most ruthless dictator.

The sometimes-contentious talks held inside the green-shuttered Metropole Hotel here were cut short when it became clear to Trump and his aides that Kim would not accept any outcome less than a full removal of crippling economic sanctions -- a request North Korea's foreign minister later denied.

Trump was surprised by Kim's demand, according to a person familiar with the negotiations, believing the young despot had come to the Vietnamese capital prepared to deal. Even though his aides warned him the North Koreans were proving intractable in preliminary talks, Trump -- a self-professed deal artist -- still felt there was a chance Kim would prove reasonable at the table.

He wasn't, as Trump learned during a lengthy negotiating session that stretched beyond its allotted time. Speaking through two female interpreters, the two men went back-and-forth for more than two hours, failing even to strike an agreement on what the term "denuclearization" meant.

Even the promise of dismantling one of North Korea's major nuclear sites fell short when Trump's aides warned him that would not match the type of sanctions relief Kim was demanding. Trump told reporters, "They wanted the sanctions lifted in their entirety, and we couldn't do that," though later in the day Foreign Minister Ri Yong Ho disputed that , stating North Korea asked only for a partial lifting of sanctions in exchange for the verified dismantling of uranium and plutonium production facilities at Yongbyon.

Whatever the case, Trump walked away -- nicely, he said -- without much clarity on what might come next in his foreign policy gambit.

He did not abandon the warmth he's shown toward Kim over the past eight months, even going as far to say he took Kim at his word when he denied knowledge of North Korea's detention of Otto Warmbier , the American student captured there only to later be returned to his family in a vegetative state. He died soon afterward.

Those remarks aside, there was palpable relief among many analysts and even some of Trump's own aides, who'd entered the talks fearful the President might agree to dramatic steps in his bid to lure Kim into getting rid of his nuclear weapons -- or to distract from the unpleasant scene of his former lawyer describing him as a racist fraudster on Capitol Hill.

According to people familiar with the conversations, Trump told some advisers ahead of the talks he did not want to appear overly thirsty to secure a deal, hoping to prove wrong the myriad analysts who predicted he'd give away the store to secure some type of progress.

He was advised by senior members of his national security team -- including Secretary of State Mike Pompeo and national security adviser John Bolton -- that he should walk away from the talks if they proved unfruitful, according to an official familiar with the summit. He was cautioned in the days and even hours leading up to the talks that North Korean negotiators were unbudging in their demands on sanctions during pre-summit talks led by Stephen Biegun, the administration's special envoy.

Pompeo, who joined Trump onstage for his concluding news conference, later told reporters as he was flying to Manila that despite eleventh-hour negotiations, it was evident the summit could end without an agreement.

"We were prepared for the potentiality of this outcome as well," he said. "And tomorrow we will get right back at it."

On Thursday, Trump still believed he could make something happen in Hanoi, one official said, and was disappointed to learn Kim was just as unbending as advertised. The evening before, top officials from his administration were still haggling to try and reach an agreement, despite indications of intransigence from the North Koreans.

"We were hopeful even this morning. We all went back and tried to sharpen our pencils and see if we couldn't get a little further and we actually did," Pompeo said as he left Hanoi. "But still, look, it is a long ways, we have always known it was a long ways."

Summit cut short

The anticlimax came into relief midday. A signing ceremony listed on Trump's official schedule only a day earlier was scrapped, a move euphemistically deemed a "program change" by the White House. A working lunch was called off, forcing the chefs inside Le Club restaurant to toss plates of foie gras and snow fish they'd prepared for the leaders. Both men peeled away in their respective motorcades well ahead of schedule.

As US officials streamed to the airport in advance of their planned departures, workers scrambled to load their bags, still strewn on the tarmac, into the belly of the plane. When Pompeo arrived to his aircraft early, the pilot wasn't even aboard.

It was a rush to the exit for a summit that sputtered despite Trump's efforts to boost interest. Even as his aides warned a second summit with Kim would lack the historic gravity of the first, Trump pressed forward, intent on recreating what he'd come to view as a highlight of his two-year presidency: the flashy breakthrough talks in Singapore eight months ago.

In the weeks and days leading up to the talks he heightened various dramas, from revealing the location to playing coy with concessions he was willing to offer. He invited along his friend, Fox News' Sean Hannity, for an interview and companionship during his two-day stay in Hanoi. He said publicly he expected heavy media interest.

Yet Trump's short stay in the Vietnamese capital seemed from the beginning to lack the kind of elaborate spectacle on display in Singapore. The making-of-history component that drew the world's attention then was absent the second time around. There were no gimmicks like the faux movie trailer predicting economic growth the President commissioned to show Kim on an iPad.

Even Trump's decision to walk away from the talks lacked drama.

"This wasn't a walk away like you get up and walk out," he said, describing a more polite exit than the table-slamming departure he staged during government shutdown talks with Democrats earlier this year.

Kim with the upper hand?

Before he arrived, there were even indications the North Koreans held an upper hand. When Kim learned midway through his days-long train journey to Vietnam that some White House reporters were staying and working from his hotel, he demanded they leave -- a dictate the White House carried out. What ensued was a scramble among television networks to relocate their gear from the space they'd rented for tens of thousands of dollars, all in the moments before Trump touched down.

The choice of the Vietnamese capital city location also amounted to an early concession: the White House had pressed for the seaside resort of Da Nang, but Pyongyang insisted on Hanoi, where North Korea maintains an embassy.

Without a joint agreement staking out the road toward North Korea's denuclearization, Trump left Hanoi in largely the same position he arrived. Once hoping the summit might prove wrong the detractors of his diplomatic gamble, instead Trump departed with all the same questions lingering about how he plans to convince Kim to abandon his arsenal.

The outcome shocked some US allies, who expected something more. South Korean President Moon Jae-in had told reporters only an hour before the talks broke up that he planned to watch the planned signing ceremony from home.

It wasn't clear why the White House listed the signing ceremony on the public version of the President's schedule the evening before, beyond sheer optimism. One official described it as a misstep since it wasn't at all clear the two sides would agree to anything during the talks.

Trump did begin the day on an optimistic note -- albeit a guarded one.

"I can't speak necessarily for today, but I can say that this -- a little bit longer term and over a period of time, I know we're going to have a fantastic success," he said at the start of the summit.

Distractions

He arrived to the talks having spent part of the evening before watching Michael Cohen, his onetime attorney who'd dramatically broken with the President , testifying before a congressional panel. He viewed part of the testimony from his hotel room in Hanoi, though not in its entirety. Some of his aides were spotted the hotel lobby watching the hearing together.

During his welcoming meeting with Kim on Wednesday evening, Trump did not appear pleased when a reporter asked about Cohen, offering a gruff "thank you" to signal the photo-op was over. The White House later limited the number of reporters who could attend a second one, citing the "sensitive nature" of the meeting. And during his concluding news conference, Trump called on more foreign reporters than American ones -- limiting the number of questions about Cohen to one.

Trump had entered the talks regretting the timing: details of the testimony in which Cohen described Trump as a cheat and liar emerged as Trump was overseeing a series of airline trade deals in the mustard-hued Vietnamese presidential palace.

"I think he was upset that he was going to have dueling shows here," said Sen. Lindsay Graham, who spoke to Trump the night earlier. "It did bother him that there was going to be a split screen going between Cohen and him meeting with Kim Jong Un."

"I said that is just the world in which you live," the South Carolina Republican said.