Trump, who made the building of a wall along the border with Mexico a central promise of his campaign, [went back on his] pledge Thursday.

“You don’t need 2,000 miles of wall because you have a lot of natural barriers,” Trump said to reporters on Air Force One during his flight to Paris.

“You have mountains. You have some rivers that are violent and vicious. You have some areas that are so far away that you don’t really have people crossing. So you don’t need that.”

“You’ll need anywhere from 700 to 900 miles,” he said.

About 600 miles of the southern border already are protected by walls, fences or other barriers. 

No need for a full border wall, Trump says – LA Times

No shit, asshat.