i Editor's Letter: Are you sleeping well at the moment, Tony Blair?

The terror being visited upon Iraq – nothing less than a vision of a new dark age – is the consequence of George W Bush and Mr Blair’s invasion and botched “reconstruction” a decade ago; and of the recent con- fused Western flirtation with Syria’s rebels. (First, helping the rebels to destabilise the Assad regime, then dithering about decisive action.)

Into this vacuum have stepped fighters determined to establish an extremist Islamist caliphate – a medieval agenda pursued with 21st-century weaponry. At Mosul, Iraq’s second-biggest city, a £25bn army fled 1,300 fighters in what my colleague Patrick Cockburn calls “one of the great military debacles in history”.

People are told to convert to fundamentalist Islam or die, military cadets machine-gunned into mass graves, minority groups slaughtered in their hundreds, many tens of thousands more fleeing into the mountains where they currently hide without water or much food.

Britain’s piddling (if well-intentioned) aid drop – “1,200 reusable water containers … and 240 solar lanterns that can also be used to recharge mobile phones”, according to Downing Street – is an affront to those who face these daily atrocities. The UK strategy of benevolent detachment is untenable.

What is our mission aim? To provide limited, short-term cover for persecuted minorities and to prevent the fall of Irbil? What then?

No economic sanctions or diplomatic channels can be used to shape events. Without escalating air strikes and deploying special forces, it is difficult to see the US and UK holding back this barbarism.

David Cameron, humbled by Parliament when he failed to win backing to strike Syria, is reluctant to ask for a military mandate from a nervous public in the months leading up to a general election.