In the field of media studies, scholars offer strategies and insights of varied quality about the profession and its ills. Alongside that work stands the practice of journalism—the bouncy flights, the lousy hotel rooms, the thrills and the humiliations of piecing together information and writing too fast, and occasionally, the loss of friends and colleagues in war zones. For a practitioner, listening to a media-studies scholar criticize work he or she has never done—even if the criticism may be justified—is a prescription for an aneurysm.

In foreign and national-security policy, there is a similar duality. There are the essay writers, the newspaper and online columnists, the scholarly Grand Strategists, and the members of Congress who travel abroad once or twice and anoint themselves experts. Then there is the actual practice of running diplomatic, intelligence, and military operations from the White House and other sections of the bureaucracy—making snap decisions with too little information, despite reading foot-wide briefing books day after day; chronic infighting among colleagues; the unrelenting tempo that leaves hardly a minute of the day for long-range thinking; the mendacity of foreign friends and enemies alike; and occasionally, the loss of friends and colleagues in war zones.

President Obama has over the last four years become a national-security practitioner in that intense, confining sense, and he had an authentic moment of succinct, controlled fury when Mitt Romney—who has never written condolence letters to the families of fallen soldiers—pressed some conspiracy-tinted, ill-conceived talking points about the attack last month at the U.S. Consulate in Benghazi, Libya, too far. The result was the most vivid moment—perhaps the most lasting moment—of Tuesday night’s Presidential debate. It exposed, too, a limitation of Romney’s that has not attracted much scrutiny: he evidently does not know very much about terrorism or Al Qaeda-related groups in Libya or anywhere else.

The episode began with a question for Obama from Kerry Ladka, one of the town-hall-style citizen-questioners in the audience. Ladka cited “reports that the State Department refused extra security” for the Benghazi consulate before the attack, and he asked, “Who was it that denied enhanced security and why?”

Obama started with an evidently rehearsed answer, referring to American diplomats in general: “I know these folks, and I know their families…. Nobody’s more concerned about their safety than I am.” He recited the advice he had given his national-security advisers after the attack. Then he turned attention away from his Administration’s possible failings and toward Romney: “Now, Governor Romney had a very different response. While we were still dealing with our diplomats being threatened, Governor Romney put out a press release trying to make political points. And that’s not how a commander-in-chief operates. You don’t turn national security into a political issue, certainly not right when it’s happening.”

In his reply, Romney rolled out his own talking point, a version of a ginned-up election season narrative Republicans have been marketing with surprising success in recent weeks. Essentially, their complaint is that the Obama Administration failed to accurately describe the Benghazi strike in public as a terrorist attack, rather than as violence that arose from a protest or a riot, because that would undermine the President’s claim that his counterterrorism policy had been a success. This is a pretty convoluted accusation on its face, and hard to follow. Romney veered toward accusing the White House of lying:

There were many days that passed before we knew whether this was a spontaneous demonstration or actually whether it was a terrorist attack. And there was no demonstration involved. It was a terrorist attack, and it took a long time for that to be told to the American people.

He also accused the President of ignoring the seriousness of the attack by flying off to campaign events in Las Vegas, as if Obama had chosen to party it up instead of attend to a national-security challenge. Obama responded with compact anger:

The day after the attack, Governor, I stood in the Rose Garden, and I told the American people and the world that we are going to find out exactly what happened, that this was an act of terror. And I also said that we’re going to hunt down those who committed this crime. And then a few days later, I was there greeting the caskets coming into Andrews Air Force Base and grieving with the families. And the suggestion that anybody in my team … would play politics or mislead when we’ve lost four of our own, Governor, is offensive. That’s not what we do. That’s not what I do as president. That’s not what I do as commander-in-chief.

Romney might have recognized that he was out of his depth and changed the subject. Instead, believing incorrectly that he had caught Obama in a mistaken claim about what the President had said in the Rose Garden, Romney plunged ahead, producing the following stanza of debate transcript poetry: