The NRO editorial on Iran is predictably alarmist, but there's one line in particular that stands out:
[Iran's acquisition of a bomb] would effectively give Tehran a veto over U.S. military action in the region.
Simply put, this just isn't true. The Soviet Union's and China's possession of nuclear weapons didn't prevent the US from invading Vietnam. US possession of nuclear weapons didn't prevent the Soviet Union from invading Afghanistan. Israeli possession of nuclear weapons hasn't prevented a series of attacks on Israel's peripheral interests. We could go on.
This kind of reasoning at NRO betrays how much we have forgotten about deterrence theory. Since I'm probably younger than any of NRO's editorialists, youth is no excuse.
Iranian possession of nuclear weapons would indeed give Iran a veto over one prospective US policy: regime change in Iran. Nuclear deterrents are useful in protecting vital interests. But the notion that an Iranian nuclear weapons capability would somehow give Iran a veto over the range of available US policies in the region is silly. It would definitely make the US think twice about the implications of its policies in the region, and perhaps make America more cautious, but given recent experience, one has to wonder how bad that would be. In the end, we don't have evidence that Iran would be any more likely to risk escalation to the nuclear level than would any other state.
This core-vs.-peripheral interests dichotomy is at the center of the literature on nuclear deterrence. If NRO wishes to cast it off in the course of advocating military action, then fine, but at least a cursory effort at dealing with the work of decades of scholarship on the topic of deterrence theory would be a welcome gesture.