Nano Wars

Imagine an arms race in nanotechnology. If and when nations begin to develop offensive nanotech devices and/or compounds, where will it end? My nanomachines against your nanomachines. Maybe it is a crazy thought but I think it is not that far fetched. Maybe we will just develop the technology then realize we can't use it safely without endangering our own troops. Maybe it will be to expensive. Maybe it will just be impossible because of the physics involved. Maybe.....