We are right to be repulsed. But I think part of our horror stems from the fact we rarely see images of American victims of war. It is the last taboo in our era of endlessly transgressive media — publishing photos or videos of injured, dying, or dead Americans in a war zone. How has this taboo been maintained? To a great degree, the reason is censorship on the part of the American government.

Beheading is barbaric. The men of the Islamic State who executed James Foley and Steve Sotloff are monsters. Yet their monstrosity does not fully explain our fury over their beheading videos, or the exhortations we have heard to not share or distribute the harrowing images .

It is an oddity of all of the violence since 9/11: Despite constant warfare and the death of more than 5,000 American soldiers (a figure that does not include American contractors, aid workers, and journalists) — not to mention the more than 50,000 wounded — we have rarely seen photos or videos of Americans in their ultimate agony. Photographers embedded with American troops have been all but forbidden from taking pictures of dead or wounded soldiers; Michael Kamber’s Photojournalists on War is filled with tales of war photographers prevented from doing their necessary work. Until 2009, it was even forbidden to take photographs of flag-draped coffins as they returned home. I once had a minor encounter with the machinery of censorship: On a military flight out of Baghdad in 2005, a military police officer confiscated my camera after I took a few shots of the coffins on board. He returned the device after deleting the pictures.

It’s no secret why the government has repressed these sorts of images. Support for the wars since 9/11 could be undermined if Americans were to see the ghastly things that happen to their brothers and sisters in combat. This is generally attributed to a lesson supposedly learned by the generals in Vietnam: If you let photographers take pictures of American dead and injured, you will lose public support for the messy undertaking of mass violence. It’s fine to disseminate pictures and video of foreign dead and wounded, which can actually help the war effort.

It is a different thing when the victims are ours. When it comes to our own citizens, the consequences of war are preferably represented in elliptical ways that do not show torn flesh or faces of the newly dead. Instead, we see townspeople lining up and saluting as a hearse drives by, we hear the sound of taps at a funeral, we remember the flag as it was placed in a brave widow’s hands, or we see a wounded veteran with a handful of pills for PTSD. It demands a mournful response rather than an informed decision.

This censorship has spawned an odd blowback. By shielding us from disturbing imagery, our government (and editors who shy away from gore) may have made us all the more vulnerable when we finally see dead Americans. This is not an abstract theory. The two disastrous invasions of Falluja during the Iraq War were sparked by pictures of the bodies of four American contractors hanging from one of the town’s bridges in 2004. It wasn’t the event itself so much as the pictures that launched such destructive fury. Confronted with these stark but complicated images, we tend to respond with a primal scream, as The New York Post did with its identical headlines for both the Falluja desecrations in 2004 and the Islamic State beheadings a decade later: “Savages.”

In the case of the Islamic State, some of the outrage is explained by the perverse pride the killers take in distributing the evidence of their crimes. But we are on a slippery slope with this indignation, because we have our own macabre mechanism for broadcasting the deaths of our supposed enemies — Central Command recently began tweeting out links to videos of air strikes in Iraq. As human rights groups have amply documented, a large number of civilians have been killed by American drones. Many Americans look at those videos and think, Got the bad guys, job well done. How many Iraqis, Afghans, Pakistanis or Yemenis look at those same videos, remind themselves of the women and children killed, and say, What savages?

In the end, it is a strange twist: Instead of pushing us away from war, as the Vietnam generals feared, images of American casualties are now driving us into the vortex. Would seeing more of it really help? Instead of reasoned discussion, might there be more howls for revenge? Or might there be shrugs of seen-it-before indifference, as Susan Sontag warned in her 2002 New Yorker essay, “Looking at War?” I wish we didn’t have to ask these questions — that there were no loathsome images to flash on our screens — and I wish we didn’t have a responsibility to look and think deeply. But we do, if the depravity of war is to be understood and, hopefully, dealt with.