Yesterday, seven car bombs exploded in Baghdad, killing some 37 people and wounding more than 100. This may or may not be a portent of things to come. But the attacks are troubling, to say the least. Whether they were executed by disaffected SoI members, recently released insurgents or Baathist holdouts is beside the point. What is significant is that a coordinated strike of this magnitude and sophistication is apparently possible again. And that again leads back to the makeshift nature of the much-advertised “calm” in Iraq. If Americans and T-walls are the only things standing between peace and mayhem, we’re in for a nasty surprise come July, when U.S. troops pull out of Baghdad. My guess is these probing attacks will intensify and turn into a full-scale onslaught, which the Iraqi army and police will be unable to check.