OUTRAGEOUS. NO Americans allowed. AGAIN. Only people present were Trump, Putin, and Putin's translator. This is a severe breach of international protocol. No other Americans there, to listen, interpret, or record. ___ WASHINGTON — Hours into a long dinner with world leaders who had gathered for the Group of 20 summit meeting, President Trump left his chair at the sprawling banquet table and headed to where President Vladimir V. Putin of Russia was seated. Earlier in the day, the two presidents had met for the first time, yielding what the Trump administration later described as a warm rapport, even as they talked about Russia’s interference in the United States’ 2016 elections. The July 7 meeting in Hamburg, Germany, was the single most scrutinized of the Trump presidency. But it turned out there was another, potentially just as important, encounter: a roughly hourlong one-on-one discussion over dinner that was only overheard by a Kremlin-provided interpreter.... There is no official United States government record of the intimate dinner conversation, because no American official other than the president was involved. “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,” said Ian Bremmer, president of the Eurasia Group, a New York-based research and consulting firm, who said he had heard directly from attendees. “They were flummoxed, they were confused and they were startled.” The encounter occurred more than midway through the lengthy dinner, when Mr. Trump left his chair and approached Mr. Putin, who had been seated next to the first lady, Melania Trump. In a statement on Tuesday, a White House official described the meeting as routine and brief, and explained the lack of an American translator by noting that the president had been accompanied by a Japanese interpreter who did not speak Russian. The official, who spoke on the condition of anonymity, said any insinuation that the White House had tried to hide the encounter was false. A second White House official confirmed that the meeting had occurred but did not offer any details, and insisted on anonymity because the discussion was private. Russia specialists said such an encounter — even on an informal basis at a social event — raised concern because of its length, which suggests a substantive exchange, and because there was no American interpreter, note taker, or national security or foreign policy aide present. “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,” said Steven Pifer, a former ambassador to Ukraine who also specializes in Russia and nuclear arms control. “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,” added Mr. Pifer, a senior fellow at the Brookings Institution in Washington.