On the PBS NewsHour this past Friday, former vice president Dick Cheney noted that “The morning after 9/11, there was a conviction that there’d be follow-on attacks—we had a lot of intelligence to that effect.” From this he concluded that “keeping the country safe for seven-and-a-half years is probably our most significant achievement during that period.”

Cheney is certainly right about the morning-after hysteria about the likelihood and imminence of follow-on attacks. As New York Mayor Rudy Giuliani recalled, at the time he and other “security experts” anticipated that “we’re looking at dozens and dozens and multiyears of attacks like this.” And in the months that followed, intelligence sources were telling rapt reporters that there were as many as 5,000 al-Qaeda operatives and supporters at loose in the country. Even two years later, during which time his agency had been able to uncover scarcely anyone in the country who even had a vague connection to al-Qaeda, FBI Director Robert Mueller testified that “the greatest threat is from al‑Qaeda cells in the U.S. that we have not yet identified," claiming that such unidentified entities had “the ability and the intent to inflict significant casualties in the U.S. with little warning."

But, counter to Cheney, the sensible conclusion is not that the country was kept safe from follow-on attacks by government action but that there were no coherent follow-on attacks to be kept safe from—though, of course, al-Qaeda leaders may have had their fantasies. That is, the popular “conviction,” as well as the intelligence that appeared to back it up, was profoundly faulty.

Ten years later, extravagant alarmism about the diabolical capacities of al-Qaeda continues. The primary justification for the war in Afghanistan remains that a Taliban victory there would permit al-Qaeda to set up a base camp from which it would finally launch its much-anticipated follow-on attack.

In some ways the process may resemble the one that followed the assassination of President John Kennedy in 1963: many found it difficult to believe that such a historic event could have been single-handedly carried out by someone so trivial as Lee Harvey Oswald. Bad guys do sometimes get tragically lucky, but that fact should not lead us to assume they are monumentally significant and capable.