Yes. Again, this will eventually happen to every one, some way. Of course nations always want to prevent this; it's part of the job of the government. But there's always long tail of very low probability, very destructive threats. You can't possibly safeguard against them. In fact, trying to do so is a sure way to trigger a fall of your nation (or at least your government), by draining your economy dry due to paranoia.

The rational thing is to address a threat proportionally to it's expected damage and probability of occurrence. When war is unlikely, you scale down your defense production; when it becomes more likely, you ramp it up - paying cold-start cost is still much cheaper than paying for ongoing readiness. If your scaling down defense makes it more likely for you to be attacked - well, that's the job of your intelligence and defense departments to track. Nobody said it's a static system - it's a highly dynamic one, that's what makes geopolitics a hard thing.