Any one who grew up in the military knows they are serious. I am an Air Force brat. I still have trouble stepping over a red line on pavement and I am 69.
I was once in a place where there was a door guarded by two Marines. They were very polite. Someone told me what ever you do, do not try to go through they door, they WILL kill you.
I was at a military site and in the safety/security training and warned of horse play. They told the story of a helicopter going along a dirt road. Some of the manual laborers riding in the back of the large open truck pointed their shovel handles at the helicopter.
A short while later the truck came over a rise and came face to face with two Humvees blocking the road with a bunch of guns pointed at them. And an armed helicopter hovering over the road with its guns pointed at them.
I don’t think that the group was arrested, but the entire company doing the work was kicked off the site.
I would often do work just outside a very secure area fence and alone. Still on the site and within a gated area - but out in the dirt and sage brush. Always made sure I was wearing my high-vis vest, truck with cones sitting on top of it to let them know I wasn’t hiding anything.
Still a bit disconcerting when the two guys come driving up, come out of their truck with their rifles at the ready and ask to see my badge and what am I doing.