As we now look back on our failure to seriously retaliate against bin Laden’s pre-9/11 acts of terrorism, we may someday look back on our failure to cancel our nuclear agreement with North Korea in the wake of its transfer of nuclear material and expertise to Syria. I’ve already argued that our inaction in light of North Korea’s nuclear aid to Syria makes nonsense of retaliatory deterrence as a strategy for discouraging nuclear attacks by terrorists. And the sad truth is, the article by Ashton Carter, Michael May, and William Perry I’ve been discussing is profoundly discouraging, even without the example of North Korea’s Syrian treachery.

Although they call for anti-terrorism deterrence based on retaliation against nuclear source countries, Carter, Ashton, and Perry place profound obstacles in the way of any actual retaliatory strike:

…Although there will be a strong urge to punish the government responsible for the leak, on the day of the attack it will probably be more in the U.S. interest to seek its cooperation than to punish it unless the leakage was deliberate…
…Tracking down the exact source of the weapon, however, could take weeks of analysis under the best of circumstances and would be impossible unless others shared sensitive data about the design of all their weapons and the composition of all their supplies of fissile materials. Such data sharing is unlikely in advance of an attack, although it might suddenly become easier as these governments strive to show they are cooperating with an angry United States.

After a terrorist nuclear strike, we are supposed to figure out who hit us using “nuclear forensics.” I have serious doubts about how possible that will be. Especially if Iran goes nuclear and a number of other Middle Eastern states follow suit, in order to balance Iran, it will become increasingly difficult to differentiate one country’s nuclear signature from another. That is especially true if, as is likely, smaller Middle Eastern powers acquire weapons through purchase, rather than through their own technology. If Pakistan sells nukes to various Sunni states, how will we know which governments actually handed off their weapons to terrorists?

Even in the best of circumstances, Carter, May, and Perry say we will need to delay retaliation in order to cooperate with the very powers who may have intentionally handed their nukes to terrorists. Supposedly, motivated by our anger, these powers will fork over sensitive and potentially incriminating information about their nuclear stockpiles and command-and-control systems.

Is this believable? What if they simply say: “So sorry, we gave those terrorists nukes just before we reformed and decided not to proliferate anymore,” or “Not our fault. That nuke was actually handed off by our out-of-control intelligence service. No way was that approved at the top.” If you think these excuses are ridiculous and unconvincing, go back and read the excuses Jim Hoagland listed for ignoring what the North Koreans have done in Syria. This Syrian incident is just the dress-rehearsal for our paralysis in the wake of an actual terrorist nuclear attack on U.S. soil. It seems likely that in the wake of the greatest catastrophe in American history, we could find ourselves “cooperating” with the very country that hit us, and talking ourselves into believing their bogus excuses. After all, it’s already happening with North Korea.

I don’t want to minimize our dilemma. The truth is, terrorists really might be able to get a bomb by stealth, using cooperative insiders in a fragmented government. Even if we can ultimately trace the source of a terrorist nuclear weapon, how will we ever know with certainty the true circumstances of its transfer to terrorists? If you think there’s controversy about nuclear intelligence now, just wait till after an attack. Given these difficulties, as I noted in “Our Fallout-Shelter Future,” a conventional response and a major expansion of our military may be as, or more, likely than a nuclear response. But what will saying that do to deterrence?

Any way you slice it, the whole problem of terrorists with nukes presents us with a series of nightmarish problems. As far as I’m concerned, this is the real reason for fighting a war on terror. It’s why we dare not risk leaving Iraq in chaos, and the field clear to a nuclear Iran.