Opinion (Timothy Garton Ash): Faced with the tragedy of Iraq, the US must rethink its whole foreign policy

Above: Members of the color guard march towards the flag pole at Camp Victory on Thursday.

You think you've reached bottom, then you hear knocking from underneath. As I follow the news from Iraq, and the American debate about it, I fear that the worst is still to come. Here's the latest twist. In desperation, and since the surge is not having the desired effect, the US military is now arming and funding Sunni gangs to help them fight other Sunni gangs linked to al-Qaida. The enemy of my enemy is my friend - even if, until only yesterday, he was the enemy I had claimed to be defeating. But how will the US military know they are not supporting killers who have the blood of American soldiers on their hands? Ah, because they will use biometric tests - retina scans and fingerprinting - on those they are arming. How reassuring.

In the short term, this modern version of a 19th century British colonial technique may actually serve to beat back the al-Qaida-related bands, as it reportedly has in Anbar province. But in the medium term, it can only fuel the civil war that most observers expect to erupt with full fury as American and British forces pull back. And that's in addition to arming the largely Shia forces of the Iraqi army. One way or another, Americans are giving Iraqis more weapons with which they can kill each other. After yesterday's attack on the al-Askari mosque in Samara, another round of Sunni-Shia violence must be expected.

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