President Trump had a private meeting with President Tusk and President Juncker at the European Union Headquarters before the bilateral session. Your pool was not brought into the private meeting and inquired with White House staff about why. Staff said the meeting was only open to official cameras from each side, not commercial press. We found video online, from host TV, showing brief snippets of their exchanges.
The first encounter came as the three presidents stood posing for photos.
Tusk told Trump: "Do you know, Mr. President, we have two presidents in the EU?"
Trump replied: "I know that."
Juncker chimed in: "One too much."
Then the three presidents walk into an adjoining room and take seats in armchairs facing each other in a circle.
Trump began by talking about his travels: "I started in Saudi Arabia. We covered a lot of countries, a lot of leaders. Some great meetings in Saudi Arabia."
Juncture said something but we could not make out what he said.
Tusk then said: "It was spectacular."
Trump replied: "It was very spectacular. I don't think there was ever anything like that. That was beyond anything anyone's seen. We went to the Pope. Very impressive. The Pope was terrific."
Here is a link to the raw video, for those interested: https://www.youtube.com/watch?v=6lErjkHjhLM