WATCH: Trump, Putin Shake Hands in Their First Encounter at G20 Summit

Trump and Putin will have their first official sit-down meeting later in the day; riots in Hamburg continue for second day

In this photo provided by German government U.S. President Donald Trump, left, shakes hands with Russian President Vladimir Putin before the first working session of the G-20 summit in Hamburg, northern Germany.
Steffen Kugler/AP

President Donald Trump and Russian President Vladimir Putin shook hands on Friday ahead of their first official meeting on the sidelines of the G20 summit in Hamburg.

In their first encounter, the two leaders were seen shaking hands and exchanging pleasantries ahead of their planned formal, sit-down meeting in video posted to Facebook by the German Cabinet. The meeting is planned for 3:45 P.M. local time. 

As officials gathered around a table, Trump outstretched his hand to Putin and then patted his elbow. Both men smiled. Another brief video clip shows Trump casually patting Putin on the back as they stand side by side.

The much-anticipated encounter comes at a pivotal time in U.S.-Russian relations. Trump will be closely watched to see if he confronts Putin over Russia's meddling in the 2016 presidential election.

U.S. lawmakers and federal investigators are continuing to look into Russia's election interference, along with possible collusion between Trump campaign associates and Russian government officials.

That puts Trump under intense scrutiny over how he handles the sit-down with Putin, a former Russian intelligence agent known to come well-prepared to meetings like this.

Trump tweeted Friday before arriving at the summit that he's looking forward to meeting Putin because they have "much to discuss."

Trump will also hold talks with Mexican President Enrique Pena Nieto.

Earlier, Trump was welcomed with a handshake from German Chancellor Angela Merkel, the summit host, and took part a photo-op with other world leaders.

At the G20 summit, leaders of the world's rich and developing nation are discussing a variety of issues over two days of meetings, including trade and climate change.

Riots

Thousands of activists seeking to disrupt the G20 summit rioted and clashed with police for a second day on Friday.

New York city mayor Bill De Blasio, one of Trump's sharpest critics, unexpectedly set off for Hamburg late Thursday to take part in protests against the G20.

Police uses a water canon while demonstrators block a street during protests against the G-20 summit in Hamburg, Germany, July 7, 2017.
Daniel Reinhardt/AP

The mayor is set to visit Hamburg and Berlin, his spokesman confirmed on Twitter, adding that he would attend several events around the G20, where protests against the summit turned violent late Thursday.

The organizers of a protest called Hamburg Zeigt Haltung (Hamburg Shows Attitude) confirmed that the mayor would be a keynote speaker on Saturday at a rally for human rights and democracy.

A police station in the Altona district of the city was attacked, while rioters threw incendiary devices by a train station in the same district and had set patrol cars on fire, the German police force tweeted.

Police advised people to avoid the area and keep their distance from the rioters.

More vehicles were set on fire on the Elbchausee riverside boulevard, but police could not immediately say how many. Black smoke could be seen rising over the west of the city.

At the same time, hundreds of demonstrators in various parts of the city tried to break through the security cordon around the meeting venue to disrupt the beginning of the summit.

Several junctions were blockaded by the demonstrators. Police have asked them to disperse in a peaceful manner.

Protesters clashed with police as the demonstrators gathered on the banks of the river Elbe and at the busy traffic junction Berliner Tor.

More than 1,000 people dressed in white and purple set off from the piers, chanting, "Get lost! Get lost!" Police used batons against the demonstrators, witnesses said. At Berliner Tor more than 200 people charged, leading to scuffles with police.

A police spokesman said the situation was "very dynamic." Police helicopters were circling overhead.

"Our aim is first to get into the blue zone, then ultimately into the red zone," said Christian Blank of the anti-globalization group Attac. 

"Once there we want to paint it with our colors according to our motto 'color the red zone.' We want to send out a signal today, we want to bring our topics today to the man and woman on the street."

The group Block G20 - Color the Red Zone had announced earlier they would use whatever means they could to disrupt the summit.

Police rounded up some 200 members of the group by St Michael's Church in the center of the city.

Dozens of police officers were injured on Thursday when they were attacked by a group of demonstrators with bottles, firecrackers and other objects, while shop windows were smashed as protesters roved through the city.

Some 12,000 demonstrators joined the protest, which was dubbed "Welcome to Hell," with 100,000 expected for the main event on Saturday.