From Omar in Baghdad at Iraq The Model blog - Forward Together Faces a Serious Challenge

... I think the problem with the new security operation is that the tactics employed so far are not new and were not adjusted in a way to meet the needs of the changing security challenges and its worst weakness is that it focused on fixed checkpoints.

My guess is that the terrorists/insurgents were frightened by the size of the operation and the amount of troops deployed but they were able to check the pulse of the new security measures and adjust accordingly, thus was the period of relative calm we had in Baghdad during the first two or three days between Wednesday and Friday.

The terrorists apparently were able to study the geographic distribution of checkpoints and a)find safe routes to move around and carry out their attacks without passing through checkpoints, and b)make the checkpoints themselves targets for their attacks...

Having checkpoints is a good idea, but these checkpoints should have no fixed places or schedules. On the other hand fixed checkpoints can be very helpful at the entrances and exits of Baghdad and these should be fortified enough to sustain themselves and repel possible attacks.

Needless to say, collecting intelligence is of critical importance to the success of the operation; no checkpoint can stop a suicide bomber from inflicting harm once he's on the street. Those must be dealt with before they wear their explosive belts or leave the garage with their explosive-laden cars, and this requires intelligence and a more aggressive tactic than fixed checkpoints.

What happened today urges an adjustment of tactics on the part of the commanders in the interior and defense ministries, and this adjustment must be made as soon as possible.