I believe that would be illegal. I suspect the reasoning is that the US is not on friendly terms with the government of Iran, which is a political squabble and

I believe that would be illegal. I suspect the reasoning is that the US is not on friendly terms with the government of Iran, which is a political squabble and not a conflict with the people therein, even though the practical consequences are indecipherable. The US military has been wrestling with that reasoning for about 20 years. If the majority of attacks and intrusions on military infrastructure originate from a single nation state and there exists evidence that most such attacks are sponsored by that nation state it would make sense to simply block all IP addresses originating from that nation state. This does not occur because the attorneys will not allow it due to both diplomatic and legal reasons.