There isn't really a good choice. Distance is really the only choice.
Once a UAV starts swarming it's first target, it becomes uncounterable.
There is also the projectile speed component. Where once the incoming projectile reaches a certain speed that countermeasures basically don't have enough time to react and won't try.
Once a UAV starts swarming it's first target, it becomes uncounterable.
There is also the projectile speed component. Where once the incoming projectile reaches a certain speed that countermeasures basically don't have enough time to react and won't try.