Certainly "might be a threat" is way too uncertain to act on. But if they're actively threatening "death to [your country]", sponsoring terrorist attacks on the

Certainly "might be a threat" is way too uncertain to act on. But if they're actively threatening "death to [your country]", sponsoring terrorist attacks on their neighbors, regularly shooting ballistic missiles at your allies, and quietly working on nukes in the background? That's a different matter. Again, not saying I agree with a preemptive strike in this case, but it's pretty easy to understand why others might think it necessary even if the short-term economic consequences of that are unpleasant.