[Karagin]

Normally minefields aren't marked until after the attacking side finds them, and the defenders would have their minefields marked on their maps by grid coordinates and standard NATO/WP markings, depending on doctrine.

The signs you posted look like what comes after they are found and thus put so everyone knows to stay away. But as you said, we don't have to use them if we don't like them. Really don't see the need to change the icons at all.