I didn't watch the full video.
I couldn't. Like most other reporters covering James Foley's death, I was anxious I'd stumble across some screen shots or a website where it'd auto-play.
You can't unsee a beheading.
In the 1970s, the Vietcong designed mantraps with sharpened bamboo spikes to maim American GIs as they prowled the Asian jungle. The idea wasn't to kill many soldiers but to instil terror in the ranks. Men would see a buddy go down in shockingly gruesome circumstances then relay details of his death to the rest of their platoon.
But war in the information age means we don't rely on soldiers' chatter to establish the enemy's barbarism. YouTube does the trick. The imagery of those first few minutes - a man kneeling and accepting an appalling fate, wishing his family goodbye - will do more to affect most of us than a conventional attack on a dozen men.
Who'd want to be President? To think, if Barack Obama had acted on the advice and criticism from some of his political opponents back when the Syrian civil war began, the United States could have directly armed Isis fighters, a la the Taliban in Afghanistan.
As it is, Isis militants are driving US Humvees and firing US arms. This is a group al-Qaeda apparently expelled for being too extreme.
But James Foley's death only perpetuates greater US involvement in the Middle East. A fortnight ago, an American public wary of returning to Iraq needed to be sold on the initial air strikes. When tens of thousands of Yazidi people were trapped on a mountain, the White House publicly justified its hits by Americanising the threat. US citizens, they said, were in danger.
It's unlikely Isis actually expected James Foley's execution to halt American air strikes.
But the horror of that video, the sheer animalism of Foley's death, will only impress on the US public that Isis needs to be stopped at all costs.
• Jack Tame is on Newstalk ZB Saturdays, 9am-midday.