(CNN) The cornerstone of President Donald Trump's foreign policy so far has largely been Donald Trump.

His personal chemistry and flattery got Kim Jong Un to the negotiating table, but now Trump's got so much skin in the game he could feel personally betrayed by Kim if the talks stall, as seemed possible this weekend.

In Kim, Trump has encountered an equally outsized figure. And over the past year, the tension between the US and North Korea felt at times like it was about two men who got into each other's heads. They alone could save this or kill it. And both seem just fine with that responsibility.

How tied is US policy to the President's gut?

Trump said in June he'd know within a minute if Kim was serious about working toward denuclearization. How?

"Just my touch, my feel," he told reporters before the Kim meeting. "That's what I do."

He's allowed many State Department positions to lie fallow in part because he's said he is the policy.

"I'm the only one that matters, because when it comes to it, that's what the policy is going to be," he said late in 2017. "You've seen that, you've seen it strongly."

At the center of so many massive global issues in the Trump era are the personal relationships and peccadilloes of Trump.

This week, he'll walk into a meeting with NATO members, traditional US allies he's openly criticized for not spending enough on defense, and many of whom he's angered with tariffs. Then he'll have a summit with Vladimir Putin, a geopolitical US foe Trump has courted and whom he believes over the US intelligence community on the issue of Russian election meddling.

The stakes of those meetings might not be nuclear war -- Trump has said the US would be in the midst of one were it not for his efforts with Kim -- but they are nonetheless important as Trump tries with his personal relationships to remake the US place in the world.

A "special bond" tested by "gangster-like" demands

But as he's finding with North Korea, so much depends on what happens after the summit, and there's more to a deal than how he gets along with another world leader.

The touch and feel were pleasing to Trump during his Kim meeting, and the two went on to rough out an agreement to come to a future denucleariztion pact. After the summit he said they had a "special bond."

"He's got a very good personality, he's funny, and he's very, very smart," Trump told Fox News . "He's a great negotiator, and he's a very strategic kind of a guy."

He later calibrated that it would be a long road to denuclearization, but at least we're not in nuclear war, which is where the US would be if it weren't for him.

Filling out the skeleton agreement Kim and Trump signed with such fanfare has proven difficult without the principals in the room. And it would be difficult regardless

And it turns out, as many experts predicted, that North Korea might not actually be interested in a complete cessation of its nuclear program.

The state news media accused the US of pushing a "unilateral and gangster-like demand for denuclearization."

Pompeo's response made it feel like the North Korean talks were slipping into the sort of standoffs that foiled previous administrations. Except in this case, Trump is personally invested. Bigly. He'll own the failure (or success) much more directly than his predecessors, who did their diplomacy with diplomats.

"A danger is ⁦‪@realDonaldTrump‬⁩ will claim he tried diplomacy and it failed b/c Kim betrayed him and now military force is called for," Richard Haas, a diplomat during the Bush administration and now the president of the Council on Foreign Relations, said on Twitter . "But a rushed summit and demands that NK denuclearize in short order or else is not a serious test of diplomacy. Need to explore interim/partial deal."

The Trump administration has suggested they prefer a deal that must include full denuclearization and not be implemented in increments.

Trump's diplomacy of personal chemistry

Trump has tried to apply his personal touch to any number of geopolitical challenges. This is not a phenomenon that's been lost on world leaders.

He might discuss imminent missile strikes in Syria over glorious chocolate cake with Chinese President Xi Jinping, as he did last year, at the same time trying to engage China's help on North Korea.

French President Emmanuel Macron showered Trump with honors like a military parade that made the US president jealous, and bro'd around Washington in an arguably desperate and ultimately futile attempt to flatter Trump into remaining in the Paris climate agreement or the Iran nuclear deal.

More recently, the leaders of the world's largest democracies used a meeting in Canada to implore Trump to change his mind on tariffs he's doled out like demerits, but he was more interested in complaining that Russia had been kicked out of the group a few years ago.

News of the tense phone calls he's had with the leaders of Canada, Mexico, Australia and the UK have seeped out during the course of his presidency.

Great relationships

But in public he's repeated like a mantra that all his relationships are great.

On North Korea's Kim: "I want to have a good relationship with North Korea. I want to have a good relationship with many other countries," Trump said. "We had great chemistry. He gave us a lot."

On China's Xi Jinping: "President Xi and I will always be friends, no matter what happens with our dispute on trade."

On the UK's Theresa May: "The Prime Minister and myself have had a really great relationship, although some people don't necessarily believe that, but I can tell you I have a tremendous respect for the Prime Minister and the job she's doing, and I think the feeling is mutual," Trump said.

On German's Angela Merkel: "I have a great relationship with Angela Merkel of Germany, but the Fake News Media only shows the bad photos (implying anger) of negotiating an agreement - where I am asking for things that no other American President would ask for!"

There are similar comments about France's Macron and Canada's Justin Trudeau. At some point it becomes a mantra: Don't believe the media, he's saying. My relationships with these people are great. And that's what matters.

Except in the case of Mexico , where Trump's belligerent declarations about NAFTA, immigrants and a border wall eclipse even his tough talk on North Korea; President Enrique Peña Nieto, who Trump had called a "friend," refused at one point to visit the White House. The President-elect, Andres Manuel Lopez Obrador , was elected promising to stand up to Trump. It's hard to see how Trump's personal chemistry leading to any breakthroughs there.

But Trump sounded optimistic.