“According to an excerpt, the president privately suggested to aides that soldiers shoot migrants in the legs, but he was told it would be illegal.”

BBC reports on the book, “Border Wars: Inside Trump's Assault on Immigration” (written by NYT reporters and published by the NYT):

Mr Trump suggested other extreme measures, according to the book.

"Privately, the president had often talked about fortifying a border wall with a water-filled trench, stocked with snakes or alligators, prompting aides to seek a cost estimate. He wanted the wall electrified, with spikes on top that could pierce human flesh," reads the extract.

Assuming — only for the sake of argument —  that the unnamed interviewees got these facts right, I would still need to have a feeling for the kind of brainstorming that was going on. This could have been lightweight banter or some way of getting to useful ideas by first loosening up and just saying every crazy thing you could think of, as if you were pitching movie ideas. Trump might have talked about a snake pit or an alligator moat, but how did he talk about it? Context is everything here, the rest is just feeding ideation.

ADDED: Trump reacted to this report in his press conference today. He denied it all and made fun of how stupid it was. He mistakenly identified the reporters as being from The Washington Post.