Norman Ornstein has an alarming piece on the Washington Post op-ed page this morning about the failure of our government to prepare to maintain continuity in the event of a devastating surprise terrorist attack with a weapon of mass destruction. This follows a June 12 op-ed in the New York Times by William J. Perry, Ashton B. Carter, and Michael M. May, stating that “the probability of a nuclear weapon one day going off in an American city cannot be calculated, but it is larger than it was five years ago.”

Building a nuclear bomb would be a formidable challenge for a terrorist group. Obtaining one would be a much easier route. How worried should we be? How real, in particular, is the loose nuclear-suitcase-bomb problem?

I’ve long been skeptical that these things could be floating around. States that build nuclear weapons are well aware of their destructive potential and go to extraordinary lengths to keep them under control.

To be sure, there have been reports pointing in the other direction. In 1997, General Aleksandr Lebed, a Russian national security adviser, told CBS’s Sixty Minutes that the Russian military had 250 such weapons and had lost track of more than 100 of them. But was Lebed in a position to know? As James Kitfield pointed out in National Journal, other Russian authorities have asserted that the KGB was in charge of these devices, which would explain why the Russian military could not offer an accurate accounting of their numbers and whereabouts.

In his 2000 book, Bin Laden: The Man Who Declared War on America, Yossef Bodansky stated that “there is no longer much doubt that bin Laden has finally succeeded in his quest for nuclear suitcase bombs.” But this claim was unsourced and seems difficult to credit. Although bin Laden has openly expressed interest in getting the bomb, and also obtained a fatwa from a Saudi cleric giving him divine permission to use one against American civilians, presumably, if he already had one in the 1990’s, we would have seen or heard it go off by now.

Still, the fact that there has been some sensationalist reporting does not mean there is no reason to worry. Pakistan’s nuclear arsenal remains a chief concern. The country hemorrhaged nuclear-weapons technology for years when its atomic-energy program was being run by A. Q. Khan, who remains a national hero. Even if Khan is no longer in the loop, other elements within the Pakistani military and nuclear establishment might well offer to supply one to al Qaeda either for cash or to earn a place in heaven.

George Tenet adds significantly to our anxieties on this score. Although there are many things wrong with his recent memoir—and I point out some of them in The CIA Follies (Cont’d.) —what he writes about this problem seems credible. Immediately after September 11, it turns out, the U.S. government was uncertain whether or not al Qaeda already had such a device:

In late November 2001, I briefed the President, Vice President, and National Security Adviser on the latest intelligence. . . . I brought along with me my WMD chief, Rolf Mowatt-Larsen, and Kevin K., our most senior WMD terrorism analyst. During the ensuing conversation, the Vice President asked if we thought al Qaeda had a nuclear weapon. Kevin replied, “Sir, if I were to give you a traditional analytical assessment of the al-Qaeda nuclear program, I would say they probably do not. But I can’t assure you that they don’t.”

Tenet continues for many pages laying out precise intelligence about al Qaeda’s continuing efforts to obtain a nuclear bomb from Pakistan and from Russia. Whatever his flaws as a CIA director, Tenet was in a position to know all that can be known about this issue. His memoirs show that we do have reason to be afraid. But we shouldn’t be quivering in our boots. Rather, even as we work to avert a disastrous vacuum from forming in Iraq, we should be prosecuting the war against al Qaeda and allied Islamic terrorists with a vigor commensurate with what is at stake.