Ethnic cleansing, systematic rape, massacres of entire communities, snipers targeting children in marketplaces – all are grimly familiar strategies of military commanders blind to the most basic concepts of human decency.
In modern times, to this list we must add the staged and filmed execution of journalists.
The cold-blooded killing of American journalist James Foley is simple barbarism. But there is nothing simple about the way it has been communicated to the world, by message-savvy terrorists familiar with the way social media works in 2014.
This is barbarism delivered in a way that is designed to play on the moral weakness of people far away from the killing fields of Syria and northern Iraq. As such, it is a barbarism all the more base for its sophistication.
Last night police officers warned that anyone in this country found to be viewing or sharing the video of Mr Foley’s execution is in danger of being arrested for committing a criminal offence.
This warning is welcome, and is common sense. This is, to all intents and purposes, what used to be called a snuff movie. It is a callous criminal act filmed in order to be shared by people who will gain a vicarious thrill from the experience of watching it. To participate in this process, by sharing or watching the video clip, is clearly a crime, as well as a sign of a warped mind.
Those who succumb to this temptation are doing the Islamic State’s job for it. They are aiding and abetting the terrorists in their gruesome and blood-soaked work.
The past 48 hours have been an agony for Mr Foley’s family, who are suffering what no-one should have to endure. The thoughts of all decent people are with them.
Who now would be in the shoes of US president Barack Obama as he weighs up his options in the face of IS threats to kill another American journalist, Steven Sotloff, unless Washington halts its bombing of insurgent positions in northern Iraq.
Mr Obama knows only too well that to ease up on this bombardment would be simply to facilitate the murderous advance of IS as it attempts to enforce its vision of an extremist Islamic caliphate across the region.
Mr Obama’s dilemmas reflect a wider question: how do you deal with people who are unwilling to negotiate on civilised terms and who hold life so cheaply?
We in the West must stand shoulder to shoulder with moderate Muslims around the world and refuse to be swayed. But holding fast in these circumstances, with more bloodshed seemingly inevitable, is going to be agonisingly difficult.
Adding to discomfort here in the UK is the knowledge that this was an act apparently committed by someone from this country, if the killer’s accent is to be believed. This was done by someone who lived in our midst.