New York Times reporters Michael D. Shear and Julie Hirschfeld Davis have covered Washington politics for a long time, but they’ve never seen anything like the Donald Trump presidency.

Shear & Hirschfeld detail the Trump administration’s aggressive tactics at the border and promises to build a wall between the United States and Mexico in their new Simon & Schuster book “Border Wars: Inside Trump’s Assault On Immigration.” The authors talked to President Trump on the record in the White House and many people around him. They discovered many fascinating details about why the administration separated families at the border and how the travel ban became law.

“One of the things that struck both Julie and I and something we didn’t expect going in was that a lot of the frustration from inside the administration didn’t come from so-called Obama holdovers or deep state people who perhaps have a different immigration agenda,” said Shear in an interview with CBS Local’s DJ Sixsmith. “In fact, it often came from people who the president had hand picked to run the relevant agencies. These people came to reject and push back against the extreme things the president wanted to do. Over time, those people were all pushed out, the most dramatic was Kirstjen Nielsen at Homeland Security. She pushed back so much that it cost her job.”

“We talk about in the book how the wall was never supposed to be… it wasn’t Trump who said I’m going to run and the wall is going to be my thing,” said Hirschfeld Davis. “He always talked about illegal immigration and his advisers early on knew that it was getting a big reactions from crowds. There were people like Steve Bannon who were on the outside at that point and understood that this could be a really powerful political theme for him.”