President Trump and Russian President Vladimir Putin spent about an hour talking privately at a dinner during the G-20 meeting in Europe, according to a source familiar with the meeting. It happened during the dinner for heads of state when at one point Trump got up from his seat and moved to sit with Putin and Putin's translator.

Why this matters: It's highly unusual for a U.S. president to meet with a Russian leader with only Russian staff present and violates national security protocol (though Trump might not have been aware of that).

Stanford's Michael McFaul, a U.S. ambassador to Russia under President Obama, told MSNBC's Lawrence O'Donnell that holding such a conversation without talking points is "very difficult — very dangerous, I would say."

Update, Trump tweets: "Fake News story of secret dinner with Putin is 'sick.' All G 20 leaders, and spouses, were invited by the Chancellor of Germany. Press knew!"

The White House said in a statement that all the leaders circulated throughout the room during the dinner and Trump spoke "briefly" with Putin and they used the Russian translator since Trump was with a translator who only spoke Japanese. Saying the meeting was hidden is "false, malicious and absurd."

Full statement

The night of the G20 summit, there was, first, a concert for all the leaders in the new Hamburg opera house. The leaders were all photographed by the press in a group photo before going in. Later that night, Chancellor Merkel hosted a dinner for leaders and spouses only, and the German government set the seating arrangements. The concert and dinner were publicly announced on both the President's schedule and the G20 schedule, with the clear understanding that all visiting leaders would be present.At the dinner, President Trump was seated between Mrs. Abe, wife of the Prime Minister of Japan, and Mrs. Macri, wife of the President of Argentina. Mrs. Trump was seated next to President Putin.During the course of the dinner, all the leaders circulated throughout the room and spoke with one another freely. President Trump spoke with many leaders during the course of the evening. As the dinner was concluding, President Trump went over to Mrs. Trump, where he spoke briefly with President Putin.Each couple was allowed one translator. The American translator accompanying President Trump spoke Japanese. When President Trump spoke to President Putin, the two leaders used the Russian translator, since the American translator did not speak Russian.There was no "second meeting" between President Trump and President Putin, just a brief conversation at the end of a dinner. The insinuation that the White House has tried to "hide" a second meeting is false, malicious and absurd.It is not merely perfectly normal, it is part of a President's duties, to interact with world leaders. Throughout the G20 and in all his other foreign engagements, President Trump has demonstrated American leadership by representing our interests and values on the world stage.