Story highlights This is the first meeting for the two men

It lasted about a half an hour

Vatican City (CNN) After a highly anticipated meeting, Pope Francis appears to have left his mark on President Donald Trump.

"Thank you. I won't forget what you said," Trump told Pope Francis, before leaving the Pope's private study after a half-hour private meeting.

Neither Trump nor the Pope revealed what their conversation entailed, but readouts from the White House and the Vatican highlighted terrorism, climate change and peace as agenda items covered.

Secretary of State Rex Tillerson, briefing reporters on Air Force One after the meeting, said terrorism and climate change came up. He said the Vatican's secretary of state raised climate change and encouraged Trump to remain in the Paris agreement.

Tillerson said the President "hasn't made a final decision," and likely will not until "after we get home."

Read More