The attacks on the two Yazidi villages in northern Iraq on Tuesday were a form of ethnic and religious cleansing - genocide, you could almost say.
The surge has forced insurgents to launch attacks out of major cities
Such things have become a part of the underlying pattern of warfare in Iraq.
The Yazidis I have met have been gentle, quiet, justifiably nervous people. Some Muslims regard them as devil-worshippers, though their beliefs are both more complicated and far more innocent than that sounds.
The situation in Iraq offers all sorts of opportunities to carry out violent attacks like these, settling old scores and wiping out religious, ethnic and political enemies.
The Pentagon and the White House have blamed al-Qaeda for these atrocities, as they habitually do for most of the violence.
The main point of the surge is political, and it is mostly directed at American opinion. The White House wants to be able to declare victory and start withdrawing
They maintain that American relations with Sunni Arabs are getting better, and that even Sunnis are turning against the extremists of al-Qaeda.
This attack may certainly have been the work of an al-Qaeda group, attacking people they would regard as heretics.
But it is equally possible that it was mainstream Sunni Arab insurgents, who in fact seem to be responsible for the large majority of killings and bombings in Iraq.
So what does all this mean for the success or otherwise of the American "surge" in troop numbers?
US President George W Bush said there would be big attacks as a result of the surge. One effect of putting tens of thousands of extra American soldiers into Baghdad and other centres of violence is that it has forced the insurgent groups to carry out their bombings elsewhere.
KEY FACTS: THE YAZIDIS
Religious sect found in northern Iraq, Syria and the Caucasus
Number about 500,000 worldwide, but largest number in northern Iraq
Doctrine is an amalgam of pagan, Sabean, Shamanistic, Manichean, Zoroastrian, Jewish, Christian and Islamic elements
Yazidis believe in a Supreme God, but do not believe in evil, sin, hell or the devil
Violation of divine laws can be expiated by metempsychosis, or the transferring of a soul from one body to another
Principal divine figure, Malak Taus (Peacock Angel), is the supreme angel of the seven angels who ruled the universe after it was created by God
In this case they attacked two virtually defenceless villages.
But for Mr Bush, the main point of the surge is political, and it is mostly directed at American opinion.
The White House wants to be able to declare victory and start withdrawing. It claims that civilian casualties in Baghdad have halved as a result of the surge.
Yet a careful examination of the figures does not necessarily support that.
The McClatchy group of newspapers, part of the American mainstream media, with a considerable reputation for honesty and painstaking accuracy in its Iraq reporting, says there were 5% more car-bombings in Baghdad in July than in December, before the surge began.
It also says the number of civilians killed in explosions is about the same.
The BBC's own monitoring of the surge also indicates that the position is less satisfactory than the White House and the Pentagon say.
Still, if the Bush administration can persuade Americans that things in Iraq are improving, then the figures are irrelevant.
It's all about politics. And according to the Los Angeles Times, next month's assessment about the surge's success will be written by the White House, instead of by the two men we were previously told would make the judgement: General David Petraeus, the US commander in Iraq, and Ryan Crocker, the American ambassador there.
Mr Bush wants to show Americans that the crisis in Iraq is improving
Both men have the reputation of being independent-minded and frank. But at a time like this, such qualities are not primarily what the White House wants.
The way history judges Mr Bush - his "legacy", to borrow the word Tony Blair always used - and the way the American electorate judges the Republican candidate for the presidency in November next year will be decided in part by the judgement on the Iraq war.
President Bush wants to persuade Americans that, in spite of everything, the war in Iraq has finally turned a corner.
The terrible loss of life among the Yazidis seems to indicate otherwise.
Yet one of the worst features of this war has been the way in which one atrocity follows another, and each seems to dim the memory of the ones that went before.