AF1 was wheels down in Brussels at 4:13pm.
Secretary of State Rex Tillerson gaggled on camera toward the end of the flight.
Highlights now and fuller quotes later:
POTUS and the pope discussed terrorism and the radicalization of young people. The Vatican's Secretary of State raised climate change in that meeting and encouraged POTUS to remain in the Paris agreement.
Tillerson said POTUS "hasn't made a final decision" on the agreement and likely will not until "after we get home."
POTUS won't make decision on Afghanistan troop levels for probably a couple of weeks.
US wants NATO to formally join the ISIS coalition. Some countries still aren't totally on board but he thinks they'll come around. Unclear if that would happen during POTUS's visit. He said the Manchester attack will strengthen he resolve of NATO allies.