Unedited, full-length videos of Islamic State beheadings are difficult to find online. YouTube has taken most down, for instance. The first notable video was recorded more than a decade ago, in May 2004, by Abu Musab al-Zarqawi, the subject of Joby Warrick’s chilling new book, Black Flags: The Rise of ISIS. The victim was Nick Berg, a twenty-six year old entrepreneur searching out opportunities in post-invasion Iraq. Zarqawi stands behind him, dressed in black with a black mask, reading a manifesto in rapid-fire Arabic. Symbolically clad in an orange jumpsuit, just weeks after the Abu Ghraib scandal broke, Berg kneels awkwardly on the floor. He has a docile, even resigned look on his face, unaware it seems of what will happen in the next five minutes and thirty-seven seconds captured by a grainy, now obsolete handheld camera.

The camera was obsolete but the images prototyped a new breed of warfare. Perhaps that’s why Berg looks so calm in the seconds before Zarqawi descends on his neck with a saw-bladed knife: he likely didn’t understand the significance of the orange jumpsuit, or the black flags hung behind him with the shahadah—There is no god but God. Muhammad is the messenger of God—lashed in Arabic calligraphy. When I first saw this video, I didn’t understand their significance either. I was twenty-four, two years younger than Berg, and a Marine second lieutenant scheduled to deploy the next month to Fallujah, the city where Zarqawi made the recording. Gathering around an office computer in Camp Lejeune with a few other lieutenants, we watched the beheading with a calm resignation. Like Berg, we were unaware of all that was to come, not only on the screen but also in Iraq.

The Islamic State’s antecedents exist in Zarqawi’s story. To understand the Islamic State’s recent blitzkrieg through the Middle East, one must understand the years of toil and near defeat that defined Zarqawi and his organization, Al Qaeda in Iraq. “He had a hero complex and guilt complex,” Warrick writes, recounting a character profile of Zarqawi conducted by Jordanian intelligence. “He wanted to be a hero and saw himself as a hero, even when he was a thug. But it was the guilt that made him so extreme.” That extremism, as manifested by severe acts of violence, proves to be one of Warrick’s central questions and one of the central questions many of us in the west have about the Islamic State: What inspires their ultra-violent, theatrical tactics?

A concept bandied about among Marine Corps leaders at the time I left for Iraq was that of a “Strategic Corporal.” The idea was that in this age of interconnectivity, the tactical actions of the most junior leaders, corporals, could have outsized strategic implications. Marine leaders used the term as a positive, but the Abu Ghraib scandal demonstrated the opposite: how choices made by a few junior soldiers could undermine an entire war effort. Zarqawi intuited the power of imagery. The orange jump suit worn by Nick Berg was not just a reference to the excesses at Abu Ghraib and Guantanamo Bay—it was a sign that Zarqawi understood the visual stage upon which he was stepping. Choreographed and disseminated correctly, a single execution could have a far greater impact than anyone had expected.

Zarqawi’s rise did not occur in a vacuum. Disastrous U.S. and Jordanian policies—grouping Islamic radicals together in prisons, dismantling the Iraqi Army, disenfranchising Sunni tribal leaders—enabled his ascent. After the U.S.-led invasion of Afghanistan, Zarqawi fled to northern Iraq, where Saddam Hussein’s secular, Ba’athist regime, though holding limited control of the region, still took active measures to root out Islamist radicals which it saw as a threat. Yet Colin Powell, in his U.N. speech justifying the invasion of Iraq, made Zarqawi’s presence in the north central to his arguments, alleging that his presence proved the Iraqi regime had granted al-Qaeda a sanctuary. Of this tenuous logic, Warrick writes, “It was like claiming that America’s twenty-second president, Grover Cleveland, had ‘harbored’ Geronimo, the famed Apache chieftain of the frontier West who attacked settlers and Blue Coats from his base along the U.S.-Mexican border.”

Pointing out the mistakes of the Iraq war is easy and Warrick only does so in service of his analysis of Zarqawi, steering away from a re-hashing of the last ten years so that his book might inform the conversation over the next ten. If the Islamic State’s acts of extreme violence seem incomprehensible to most, Warrick’s gripping chronicle of Zarqawi’s life lays bare not only his evolution into a fanatic but the logic of such fanaticism. It’s a logic rooted in economic and social disparities, decades of oppression by western-backed autocrats, all fueled by a religiosity that grants its adherents a place in an Islamic narrative of conquest and liberation reaching back more than one thousand years. Though westerners might be uncomfortable with this logic, it is one we must understand if such ideologies are going to be countered in Iraq, Syria, north Africa, and even Europe and the United States.

Since the Berg video, many more videos have appeared and certainly there will be many more. I also imagine they will begin to mean less and less as western audiences become inured to such images, no matter how ghastly. I also imagine members of the Islamic State, al-Qaeda and other groups will adapt their tactics accordingly. In 2002 the U.S. routed al-Qaeda in the mountains of Afghanistan. After al-Qaeda regrouped, the chief of intelligence for the Joint Special Operations Command, Michael Flynn, noted, “They got better because they saw how they were defeated.” Let’s hope the same can one day be said about our current efforts in the region.

Elliot Ackerman is the author of “Green on Blue” and the forthcoming novel “Dark at the Crossing.” He served multiple combat tours in Iraq and Afghanistan and currently lives in Istanbul.

Caption: Posters in Baghdad showing Al-Qaeda in Iraq leader Abu Musab al-Zarqawi, 2005.