Donald Trump had a second, undisclosed meeting with Russian President Vladimir Putin on July 7 at the G20 summit in Hamburg, Germany.

Defying standard operating procedure, Trump took no other US official into the session with Putin, who was accompanied by a translator.

Earlier in the day, Trump and Putin had had a publicly-announced 2 1/2-hour discussion. Trump brought Secretary of State Rex Tillerson, but left behind other officials — notably National Security Advisor H.R. McMaster and his Russia specialist Fiona Hill — who had a more sceptical view of Moscow. Putin was accompanied by Foreign Minister Sergei Lavrov, and both leaders had translators.

Hailed by the White House as a success, the meeting soon fell into controversies. Putin and Lavrov cornered Trump by announcing that the US President had accepted Putin’s denial of any Russian intervention in the 2016 US Presidential election. Trump’s proclamation of a joint cyber-security team with Moscow was met with astonishment and ridicule, and he backed away within 72 hours.

The second, private encounter came just over halfway into a banquet for the G20 leaders. Trump left his chair at the and headed towards Putin. The two men then disappeared for an hour.

Leaders at the table expressed astonishment, according to sources — apparently from foreign states — who have given the information to US outlets. Ian Bremmer, president of the Eurasia Group, summarized his information from attendees:

Pretty much everyone at the dinner thought this was really weird, that here is the president of the United States, who clearly wants to display that he has a better relationship personally with President Putin than any of us, or simply doesn’t care. They were flummoxed, they were confused and they were startled.

On Tuesday, a series of former US officials talked about the diplomatic risks of Trump going unaccompanied into a discussion with the Russian leader. Steven Pifer, a former ambassador to Ukraine, explained:

We’re all going to be wondering what was said, and that’s where it’s unfortunate that there was no U.S. interpreter, because there is no independent American account of what happened.

If I was in the Kremlin, my recommendation to Putin would be, “See if you can get this guy alone,” and that’s what it sounds like he was able to do.

But the White House insisted there was nothing unusual — “the insinuation that the White House has tried to ‘hide’ a second meeting is false, malicious, and absurd” — and Trump then went to social media to denounce “sick” news reports. Confusing the private meeting with the public banquet, he tweeted:

White House Press Secretary Sean Spicer tried the line that the meeting lasted far less than an hour and was only “pleasantries and small talk”. The White House said Trump was unaccompanied because his translator did not speak Russian.

The revelation comes amid the escalating furor over possible Trump-Russia collusion in the 2016 US election, spurred by the disclosures around a June 2016 meeting in Trump Tower between Donald Trump Jr., Trump Sr.’s son-in-law Jared Kushner, and campaign manager Paul Manafort with three Kremlin-linked envoys.

The Daily Show has a bit of fun with the second Trump-Putin meeting: