Yes, it can be won
No, it can't be won
With preemptive planning and defence tech. No war is unwinnable if you have appropriate defensive/offensive capability. The cost could be high though.
If we kill more of their people than they kill ours, that counts as a victory.
If we did manage to decimate every single opposing culture on the planet, the radiation and nuclear waste left behind would deem this planet practically uninhabitable.
Nuclear Winter!!!!!!! I always wanted one since I love Winter
War never has a true victor. Nuclear war is ever worse.