HAMBURG — President Trump attended the G-20 summit in Hamburg, but he wasn't really a part of it.

Instead, Trump used the conference space generously provided by his host, German Chancellor Angela Merkel, to conduct a series of his own mini-summits — separate on-on-one "meetings on the sidelines" with other world leaders where Trump pursued his own agenda.

He met with Russian President Vladimir Putin about his interference in western elections. He met with leaders in Asia about North Korea. And he met with trading partners throughout the world in a two-day binge of talks.

This focus on one-on-one meetings, which ended with Trump declaring newly created great friendships with world leaders, meant that he often stepped away from the bigger meetings. On Saturday, he left his daughter Ivanka to represent the United States on the floor of the G-20 while he met with the president of Indonesia.

And when the rest of the summit agreed that the Paris climate agreement was "irreversible," Trump withheld U.S. support for that part of the final communique.

The dynamic was apparent from the very beginning, while posing for the "family photo" with other world leaders. It was Merkel taking center stage, her bright red jacket standing out all the more from a sea of black business suits.

Trump was on the outskirts, unable to shove his way through the crowd to get to the center as he did with the Montenegrin prime minister at the NATO summit in May. Instead, he was in the corner, engaged in small talk with French President Emmanuel Macron.

It was a visual representation of Trump's brand of diplomacy. While he loves to command a room, he prefers to work one-on-one as opposed to groups.

If President George W. Bush was accused of being a unilateral president, too often going it alone on the world stage; and President Barack Obama was a multilateral president, seeking broad consensus on issues like climate change, trade and security —then Trump is a bilateral president, seeking to make deals one at a time.

That preference for bilateral relationships is based on personality, experience in business and a philosophy that puts narrow national interests ahead of broader global concerns like wealth inequality, refugee resettlement and climate change.

It's a worldview Trump articulated in his speech in Warsaw on Thursday, where he extolled the virtues of national sovereignty, self-determination, strong borders and nations paying for their own defense.

While he pledged to defend NATO allies from attack — something he pointedly did not do at the NATO summit — he also expressed a deep skepticism of international bureaucracies.

Bureaucracies like the G-20. the group of 19 of the largest national economies (plus the European Union) founded in 1999 to address the world's most pressing economic issues.

Trump now has three major foreign summits under his belt, plus two other smaller group meetings in Saudi Arabia and Poland. While he often seemed on the sidelines, aides say Trump will not "lead from behind."

Trump is driven by a "clear-eyed outlook that the world is not a 'global community' but an arena where nations, nongovernmental actors and businesses engage and compete for advantage," national security adviser H.R. McMaster and economic adviser Gary Cohn wrote in the Wall Street Journal after his first foreign trip.

Trump and Putin's shared worldview

That's a view of the world largely shared by Putin. He, too, favors the one-on-one relationships to broader action.

"If we want to have a positive development through bilaterals and be able to resolve most acute international problems, then definitely we need personal meetings," he said in his meeting with Trump Friday.

As cameras clicked and reporters shouted questions, Putin motioned to the journalists and asked Trump, "These are the ones hurting you?”

"These are the ones. You're right about that,” Trump said.

Putin's reference to Trump's war with the media was no accident, said Stephen Sestanovich, a former ambassador-at-large to the former Soviet Union during the Clinton administration. "I’m sure Putin finds that very simpatico."

"Trump clearly thinks bilateral relationships serve the U.S. best in general, but there’s a separate reason for dealing with Russia one-on-one," said Sestanovich, now a professor at Columbia University. "Putin is a semi-pariah internationally, especially now that the G-7 kicked him out three years ago. He too deals with many countries bilaterally, because Russia isn’t in all that many global clubs."

Trump's critics say his fostering of a Putin relationship in particular is a dangerous gambit. While Trump pressed Putin about his involvement in a campaign to interfere in the 2016 presidential campaign, Putin says Trump ended up agreeing with him that there was no such interference.

"When it comes to Russia, I am dumbfounded," said Sen. Lindsey Graham, R-S.C., on Meet the Press Sunday. "I am disappointed and, at the end of the day, he’s hurting his presidency by not embracing the fact that Putin’s a bad guy who tried to undercut our democracy and he’s doing it all over the world."

White House Chief of Staff Reince Priebus said Sunday that Trump does believe Putin meddled in the election, and simply chose to move on to other topics.

He said the summit showed Trump "standing up for the American people."

“I think the American people should look at that as a massive positive about this president, that you have a president that doesn't just show up at the G-20 and sink into his chair and just suddenly agree with all of these European leaders across the table when it comes to issues that he disagrees on,” Priebus told Fox News Sunday. “The president has made it very clear that he doesn't believe the Paris agreement is fair.”

But even as Trump rankles Europe, he seems to be focusing more attention to the Pacific Rim — where Trump is hoping to sign a series of trade deals to replace the Trans-Pacific Partnership he tore up his first week in office.

Trump's formula

Those meetings illustrate Trump's tried and true formula for opening a bilateral meeting: Emphasizing the closeness of the relationship, and then launching right into a discussion about trade:

• With Indonesian President Joko Widodo: “We've become friends, and we're going to be doing a lot of deals together — trade deals.”

• With Prime Minister Lee Hsien Loong of Singapore: “The Prime Minister of Singapore – we're very close, the relationship is very close, and we expect to do some excellent things together in many ways.”

• With Mexican President Enrique Peña-Nieto: “It's great to be with my friend, the President of Mexico. And we're negotiating NAFTA and some other things with Mexico, and we'll see how it all turns out.”

• With South Korean President Moon Jae-In: “We had fantastic dinner at the White House – accomplished a lot,” he said. “We are renegotiating a trade deal right now as we speak with South Korea, and hopefully it will be an equitable deal.”

• With Chinese President XI Jinping: “We are developing, and have developed, a wonderful relationship,” he said. “And I'm sure that whether it's on trade or whether it's on North Korea, or any of the many things that we will be discussing, we will come to a successful conclusion.”

Treasury Secretary Steven Mnuchin said the talks behind closed doors were "very, very substantive."

“These were not just relationship builders," he said.

Trump sends mixed messages on Putin, Russian hacking

Trump sits out on climate agreement: At G-20 summit, it's 19 against U.S.