"Tal Afar is quickly becoming a symbol of the failure of US policy in Iraq.

"The Americans have been in there twice before as part of two huge operations. They pacified the situation, but each time they handed it over to the Iraqi security forces the problems started again.

"There are a number of reasons for this.

"Tal Afar is a very sensitive place. It is ethnically very mixed and it is also a big smuggling route from Syria towards Mosul. In Mosul there is a very large Sunni population with links to Saddam Hussein. He did much of his recruiting there, and many of the current Sunni residents of the area were his officers until the Americans sacked them. This has created a pool of resentment and an excellent recruiting ground of Sunni anger in the area.

"In addition, the fact that off-duty police officers were involved in today's shooting implies that the Shia militias, in particular the Mahdi Army, are having no difficulty in recruiting members of the local police to their cause. These are the very police that the Americans were counting on to ensure calm and order to the town when US troops left.

"The implications of what happened yesterday in Tal Afar are massive as the American troop 'surge' was meant to have stopped precisely this type of thing. Instead, the indications are that it has just led to a renewed push by the insurgency to launch bigger and bigger attacks to wreck any progress US troops are making.

"What the insurgents are trying to do is to create so much heartache and instability that people whose nerves were already frayed to breaking point will snap and vow to take revenge. In doing so, they calculate that the instability will become so great that the US policy in the country would be bound to fail. Tal Afar is an example of how this escalation policy is working.

"What we have also seen, in response to the American surge, is a shift in the methods of the violence in and around Baghdad, but not a drop in the violence overall.

"As a result of the extra troop numbers and a toughening up of checkpoints, the number of people being kidnapped has dropped, but the number of car-bombs has increased.

"This is mainly because while smuggling kidnapped people through checkpoints is very difficult, smuggling car-bombs is easier because the Iraqi police and army are still barely checking for them.

"So as the security plans change, the tactics of the guerrillas also change.

"People who I have spoken to do not have much hope that things will improve in Iraq. They say: 'In this country, people are more interested in revenge than reconciliation.'

"The outlook is bleak."

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