First of all, here’s the problem: barbed wire can be destroyed with the J button or dynamite, but the wreckage will stay and continue to cause damage. This is very noticeable if it was built to float in the air.
In other words, if barbed wire is placed at the entrance to a bunker, it is impossible to enter without taking damage.
Sandbags disappear when destroyed, so this should not be a specification of the game.
This is a problem that should be fixed.
Also, if you repeat this operation, you will not be able to build. When you open the building menu, you will see the message “The limit has been reached” even though the building counter has not decreased.
This means that the barbed wire you destroyed with the J button or dynamite has not been destroyed in the system.
This must be a bug.