Watch Russian President Vladimir Putin and Saudi Crown Prince Mohammed bin Salman's exuberant handshake at G-20

  • Russian President Vladimir Putin and Saudi Crown Prince Mohammed bin Salman on Friday warmly shook hands when they were seated together at the G-20 economic summit in Argentina.
  • The hearty hello came two days after the Senate overwhelmingly voted to call for an end to U.S. involvement in the Saudi-led war in Yemen after weeks of suspicion that the crown prince had ordered the killing of journalist Jamal Khashoggi.
  • The bonhomie also came after Russia seized several Ukrainian naval ships and their sailors, and after Trump's former personal lawyer pleaded guilty to lying to Congress about an aborted plan to build a Trump Tower in Moscow.

Two of President Donald Trump's favorite strongmen — Russian President Vladimir Putin and Saudi Crown Prince Mohammed bin Salman — warmly shook hands with one another, smiled broadly and laughed when they were seated together Friday at the G-20 summit in Argentina.

Twitter quickly labeled the Putin-MBS palm slap a "bro-five."

But it wasn't a joking matter for Garry Kasparov, the Russian who is both a former world chess champion and an outspoken critic of Putin, who retweeted the video with the caption: "Murder Incorporated."

Their hearty embrace came two days after the Senate overwhelmingly voted to call for an end to U.S. involvement in the Saudi-led war in Yemen, and after weeks of strong suspicion that the Saudi crown prince had ordered the brutal killing of journalist Jamal Khashoggi in the kingdom's consulate in Istanbul last month.

WATCH: Who is Mohammed bin Salman?

The bonhomie in Buenos Aires came at the end of a week in which Russia seized several Ukrainian naval ships and their sailors in the Black Sea — and in which Trump's former personal lawyer Michael Cohen pleaded guilty to lying to Congress about the extent of Trump's involvement and knowledge of an aborted plan to build a Trump Tower in Moscow.

Special counsel Robert Mueller is continuing to investigate Russian efforts to influence the 2016 president race that ended in Trump's victory, as well as possible collusion by the Trump campaign in that skulduggery. Trump adamantly denies any wrongdoing.

Trump, right after Cohen's guilty plea Thursday, told reporters he planned to meet with Putin at the G-20. An hour later, however, the president tweeted that the meeting was canceled in light of Russia's refusal to release the Ukrainian ships and sailors.

WATCH: What is the difference between the G-7, G-8 and G-20?

Yet, a Kremlin spokesman said Friday that Putin and Trump would hold a brief, impromptu meeting at the summit, even as the White House continued saying there was no scheduled meeting.

Putin was accused in September by Britain's security minister of being "ultimately responsible" for the alleged attempt in May by Russian intelligence officers to murder former Russian double agent Sergei Skripal and his daughter in England with a nerve agent.

And for years before that, a number of Putin's critics have died from violence or other under unusual circumstances.

While the CIA has "high confidence" that Crown Prince Mohammed ordered Khashoggi's murder, Trump has given the crown prince — who denies doing so — the benefit of the doubt, saying last week that "maybe he did and maybe he didn't!"

The president also has recently praised Saudi Arabia for falling oil prices even as outrage continues over the murder of Khashoggi, a resident of the United States who contributed to The Washington Post.

In July, Trump sparked outrage at a news conference in Helsinki, when he likewise sided with Putin, who was standing next to him, over American intelligence agencies who say Russia meddled in the election.

"My people came to me, (Director of National Intelligence) Dan Coats came to me and some others. They said they think it's Russia. I have President Putin. He just said it's not Russia. I will say this, I don't see any reason why it would be," Trump said.

The since-deceased Sen. John McCain, R-Ariz., said at the time that Trump's joint news conference with Putin was "one of the most disgraceful performances by an American president in memory."

"The damage inflicted by President Trump's naivete, egotism, false equivalence, and sympathy for autocrats is difficult to calculate," McCain said.