Moscow (CNN) Gatherings of world leaders are often about the absence of substance. Several news cycles from now, few will remember what was discussed at the recent G20 summit in Buenos Aires.

Never mind that US lawmakers and other world leaders have castigated the Saudi crown prince over the murder of journalist Jamal Khashoggi. Putin's embrace of MBS telegraphed a message of unabashed support for Saudi Arabia, even as the Trump administration tries to contain the political fallout from the murder.

Putin is certainly one to sense an opening. His personal outreach builds upon a burgeoning oil alliance between Moscow and Riyadh . Perhaps more importantly, it comes as his well-established rapport with US President Donald Trump is starting to look a little bit wobbly.

And it accompanies a confrontation with the US over arms control: US Secretary of State Mike Pompeo announced this week that the US will stop adhering to a decades-old nuclear treaty in 60 days unless Russia returns to compliance with the agreement.

US President Donald Trump shakes hands with Russian President Vladimir Putin before the Helsinki summit in July 2018.

Pointed snub to Putin

How quickly things have changed since the Helsinki summit in July. Less than half a year ago, Trump stunned observers by appearing to side with Putin over the US intelligence community, saying he took the Kremlin leader at his word over his denials of meddling in the 2016 US presidential election.

The G20 summit was originally billed as a sort of Helsinki 2.0: Trump and Putin were supposed to have a lengthy meeting on the sidelines of the summit, where they would have wide-ranging discussions about matters of strategic importance.

That bilateral meeting, however, was scuttled after an incident around the Kerch Strait, where Russian and Ukrainian vessels clashed at sea on November 25. The confrontation between Kiev and Moscow quickly ramped up: Russia seized three Ukrainian navy ships and detained 24 service members, and Trump cancelled his meeting with Putin , saying it would be inappropriate for him to meet while the crisis was unresolved.

It was a pointed snub to Putin, who said it was a "pity" that he was unable to have a full-fledged meeting with Trump, because, as he put it, "the time is ripe particularly with the problems around strategic stability."

Trump's volte-face came after his longtime former attorney Michael Cohen leveled fresh allegations in court about the President's business dealings with Russia. And the Russians were quick to cast doubt on Trump's reasons for canceling the bilateral meeting.

Russian Foreign Ministry spokesperson Maria Zakharova last week suggested that the "US domestic political situation" was the real reason for the cancellation of the G20 meeting.

"Was the provocation organized by Kiev in this region the real reason for cancellation?" Zakharova said, referring to the Kerch incident. "Publicly, we heard just such an explanation, we took note of it. Is this a reality? I think that you still need to look for answers in the US domestic political situation. The dominant factor in making a decision is domestic political realities in the US."

Kremlin-aligned Russian media had a field day with Trump's cancellation.

Pro-Putin news anchor Dmitry Kiselev highlighted the Putin-MBS high-five on his program, adding: "A dissonant contrast to everyone's mood was Trump, looking morose, sitting there with crossed hands as if he is trying to shield himself from everyone else, scared of blurting out something unnecessary. Looks like he was just not prepared for a coherent meeting with Putin."

Vladimir Soloviev, another pro-Kremlin presenter, took a similar dig at Trump.

"Trump's volatility and unpredictability is the new brand of the White House," he said.

Reset that never came

In terms of Russia's perception of Trump, things have come a long way since the 2016, when his election victory was treated as a potential breakthrough in Russian-American relations.

Konstantin Kosachev, a Russian senator who is chair of the Federation Council's Committee on Foreign Affairs, summed up the new Russian pessimism about Trump and the United States in an interview with CNN. Like many Russian official observers of the American political scene, Kosachev believes Trump is hamstrung by the ongoing probe by special counsel Robert Mueller.

"The current American policy towards Russia is not about Russia or the foreign policy of the United States," he said. "It's about the domestic policy of the United States. America is still captured by these disagreements and emotions from the previous presidential campaign. Mr. Trump is being heavily attacked. And one of the tracks of this attack is the Russian meddling in the American elections, which has never been proved by any evidence. So, I believe that our bilateral relations are kept hostage by certain internal political interests of certain political forces inside the US. And I am afraid we will trapped in this situation until the next presidential election."

It's a pivotal moment in Washington, with special counsel Robert Mueller on Friday outlining a previously undisclosed set of overtures and contacts between the Trump campaign and Russian nationals.

Federal prosecutors said for the first time that Michael Cohen acted at the direction of Trump when the former fixer committed two election-related crimes during the 2016 presidential campaign.

Separately, Mueller said Friday that former Trump campaign chairman Paul Manafort lied about five major issues after agreeing to cooperate with prosecutors, including his "contact with administration officials."

The accusations by Mueller add to growing signs that the special counsel's team has a wealth of evidence about contacts between people close to Trump -- even in the White House -- and Russians during the 2016 campaign.

It also comes after Mueller told a federal court that Michael Flynn, Trump's former national security adviser, had given "substantial assistance" to the Russia investigation and should not receive jail time.

But with the Mueller probe coming to a head, Russia's line has been consistent: There was no meddling, therefore the probe is groundless.

Asked in a conference call this week with reporters to comment on the Mueller probe, Kremlin spokesperson Dmitry Peskov was dismissive.

"We have enough other concerns, so this is not a priority topic for our attention, frankly speaking," he said. "I do not know what kind of breakthroughs there could be. That [information] now available to the public in many respects is mystifying and a raises a huge number of questions, we have repeatedly cited examples of the absurdity of such accusations."