U.S. President Donald Trump checks time prior to a dinner at the Art and History Museum at the Parc du Cinquantenaire during the NATO Summit in Brussels, Belgium July 11, 2018. Geert Vanden Wijngaert/Pool via REUTERS

BRUSSELS (Reuters) - U.S. President Donald Trump went on a fresh attack against NATO allies’ spending and European trade practices in a closed-door session at a NATO summit on Thursday, two sources told Reuters.

NATO leaders then asked non-NATO partner countries Ukraine and Georgia to leave the room for an unscheduled, allies-only session, the sources said.