Fatima posted a link, and I would have sworn I copied the images she linked to...Oh, just realized the first one is a Getty image, so probably got taken down. Second one doesn’t say Getty but not posting just in case.
Here are links: barbed wire coils on the inside of the fence, and bolts on the outisde.
https://twitter.com/paint_texas/status/1350495683476918272/photo/1
https://pbs.twimg.com/media/Er3sj8DXUAIBxlr?format=png&name=small
My thought on barbed wire inside vs. outside. In my younger years, I could climb a chain-link fence, get to the top, and jump down on the other side. Granted, none were higher than 6 foot, but a seasoned person with no fear of heights could do the same with a 9 or 10 foot fence no problem.
Let me add, if the barbed wire is on the outside, I’d just leap a bit farther out and avoid it. But if it’s on the inside, it presents an additional obstacle.
Of course, at my age now, I’m not hopping any fences, regardless of barbed wire status.