In Korea I worked at a place that very intentionally looked like nothing. We took buses there, and loaded and unloaded at a well guarded and hidden entrance.
It was possible for a civilian to wander on foot close to that entrance.
One time an old guy selling his wares got a bit close. I happened to be right there when it happened.
It was three "move along sir"s, followed by three men looking very serious, pointing guns at the poor dude.
Remarkably, that seemed to encourage him more that he wanted to see beyond the entrance. He didn't seem to take it seriously, even with M-16s in his face.
After about 30 seconds, more guards came from nowhere and the guy was face down in the dirt.
While he was facedown, he got a lecture in Korean that I couldn't understand.
I did get the feeling, though, that something clicked and he wouldn't be back.