When President Trump shakes people's hands, the world is watching. Here's why. (Peter Stevenson/The Washington Post)

HAMBURG — The two men sat feet apart.

Russian President Vladimir Putin wore a coy smile. President Trump settled into his familiar glower.

Their relationship is a topic of global wonder. Possible Russian interference in the 2016 U.S. presidential election, meanwhile, is the focus of several inquiries. And Friday they finally held a face-to-face meeting. Every detail carried clues of how the two leaders perceived one another and what approach each would take in managing a moment strewn with potential land mines.

Trump, leaning forward with his fingertips pressed together, was first to speak.

“It's an honor to be with you,” he said. “We look forward to a lot of very positive happenings for Russia and for the United States and for everyone concerned.”

Trump then turned quickly to Putin and stretched out his arm, his palm face up for a handshake.

Putin obliged. He leaned forward and grasped the American president's hand, nodding his head. Both men smiled and then quickly withdrew. It was brief, not overly affectionate but not chilly either.

Trump then turned back to his Russian counterpart and invited him to give his own appraisal of their first chance at an in-person conversation.

“I'm delighted to be able to meet you personally,” Putin said. “And I hope that, as you have said, our meetings will yield positive results.”

Earlier in the day, a brief encounter between the two was captured behind the scenes of the Group of 20 summit by the shaky hands of an official German videographer.

As world leaders socialized and made small talk before the first meetings of what is already a contentious summit, it was Trump who approached Putin, who stood with his back against a wooden room divider.

Trump strode up, right arm extended wide, as Putin held his arm closer. To Putin’s left, Japanese Prime Minister Shinzo Abe stood chuckling, perhaps amused to be privy to the initial encounter.

Trump and Putin locked hands, pumping slightly, as the U.S. leader brought his other arm up to pat Putin a few times on the forearm. Putin raised his left hand to make a point. It wasn’t clear what the two leaders were talking about. Putin’s English is not fluent, and there were no translators in the room. Trump does not speak Russian or German, Putin’s two languages.

Later, the two men stood about three feet from each other at a cocktail table, smiling broadly. Trump gave Putin some friendly back pats.

Putin said something to European Commission President Jean-Claude Juncker, who smiled back at him.

In the end, the Trump-Putin handshakes appeared to be normal ones between equals, a notable development after many of Trump’s grip-and-grin encounters turned into battles of will. Trump has made an art of the powerful pump, then the yank, a move that has nearly toppled other leaders.

Peak handshake may have been reached in May in Brussels with French President Emmanuel Macron, who gripped Trump’s hand long after the U.S. leader wanted to disengage, then bragged about it later to a French newspaper.

In an encore encounter, Macron and Trump spoke to each other briefly before leaders sat down for their lunchtime meeting. Trump patted Macron on the back. It was not quite a whack — but it was firm enough to require a windup of his arm. Macron smiled, and the two men engaged in a brief man-hug.

It was unclear whether Trump realized that the images of the backstage meeting with Putin would be made public. The video was released by the German government shortly after the encounter.

When Trump met Russian Foreign Minister Sergei Lavrov in the Oval Office in May, the White House barred American photographers from the encounter but allowed in a Russian photographer whom they had been told was Lavrov’s official accompaniment. They were blindsided when the state-owned news agency TASS published the chummy photos.

Kremlin spokesman Dmitry Peskov said Trump and Putin had exchanged pleasantries and said “they’d see each other later.”

In two tweets earlier Friday, Trump said he was looking forward to the 35-minute meeting, saying: “I will represent our country well and fight for its interests!”

The interaction was more fluid than that of Putin and British Prime Minister Theresa May, who leaned awkwardly toward the Russian leader for a quick hand clasp across the table.

But the prize for friendliness might go to Macron and Canadian Prime Minister Justin Trudeau, who resumed a bromance first sparked in May at the Group of 7 summit with a warm hug, then some cocktail chatter. Both men are fluent in English and French.