Drudge’s breathless red-font headline: “NO NUKES: EVEN IN SELF-DEFENSE!” As I read the story, though, the new policy still leaves open the possibility that we might initiate a nuclear exchange. It all depends on whether the target country has nukes of its own and whether it’s in compliance with the Non-Proliferation Treaty.

Let’s explore the nuance.

It eliminates much of the ambiguity that has deliberately existed in American nuclear policy since the opening days of the Cold War. For the first time, the United States is explicitly committing not to use nuclear weapons against non-nuclear states that are in compliance with the Nuclear Non-Proliferation Treaty, even if they attacked the United States with biological or chemical weapons, or launched a crippling cyberattack

White House officials said that the new strategy will leave open the option of reconsidering the use of nuclear retaliation against a biological attack, if the development of such weapons reaches a level that makes United States vulnerable to a devastating strike.

Mr. Obama’s new strategy is bound to be controversial, both among conservatives who have warned against diluting America’s most potent deterrent, and among liberals who were hoping for a blanket statement that America would never be the first to use nuclear weapons.

Unless I’ve misunderstood, we reserve the right to nuke the following, whether in self-defense or otherwise: (1) nuclear states, (2) non-nuclear states that are in violation of the NPT (i.e. Iran), (3) non-nuclear states that attack the U.S. with bioweapons, but only if they possess a stockpile large enough to pose a risk of a “devastating strike.” I hope I’ve misunderstood that last one; the idea of Obama explaining to Americans that, yes, 50,000 people may be dead of smallpox but we can’t nuke country X because they don’t have a big enough stockpile of the virus yet is dark comedy gold.

The idea here, of course, is deterrence — comply with the NPT and you have nothing to fear — but (a) no one, least of all Iran, thinks Barack Obama’s going to use nuclear weapons against targets inside a non-nuclear state whether it’s following the NPT or not, and (b) everyone, including Iran, understands that a devastating attack on the U.S. by whatever means will create such unbearable pressure on the president to retaliate that these rules will be revisited instantly. It’s the nuclear equivalent of his interrogation protocol, essentially. America does not and will not torture captured terrorists as a matter of national policy — but if the CIA really, truly believed that a bomb was about to go off somewhere, don’t be surprised to see that policy politely ignored, to great public acclaim for Obama afterwards for having done what he needed to do to try to get the information.

All this is, really, is a symbolic gesture of good faith to put pressure on Russia and China to reduce their own stockpiles. Why we think they can be trusted to do that, especially when the United States is handing them a tactical advantage by reducing its own stockpiles unilaterally, is beyond me. But then it’s also beyond me why Obama would suspend development on any new forms of nuclear weapons, which the new policy also demands. New weapons, I assume, would be smaller and more precise, in the bunker-buster mold; there’s certainly no pressing need for state-of-the-art 100-megaton monsters when the chief nuclear threat at the moment comes from small non-state groups like Al Qaeda.

Exit question one: In limiting the nuclear deterrent to nuclear weapons (and, in certain cases, biological attacks) instead of WMD generally, doesn’t this create an incentive to focus on developing bio and chemical weapons? In most cases those are less dangerous than nukes, but nukes are also harder to develop and more easy to monitor. Do we really want tomorrow’s A.Q. Khans focusing on smallpox instead? Exit question two: If the point here is to raise the taboo on using nuclear weapons, doesn’t that actually make them more enticing for jihadi fanatics?