it's not about unable to defend is about a bug that needs to be worked out.
semp
I'll type this slow so you can understand.
The game collision model causes damage between moving objects (planes hitting planes) and non moving objects (planes hitting trees, buildings, ground)
If you turn on the collision model for the GV's, each time you hit a tree or a building with your tank, it will fall apart or explode (just like when a plane hits a tree or a building).
Get it yet?