Jim Henley seems very right about this. In an effort to protect themselves from getting blown up, U.S. troops in Iraq have increasingly found themselves firing on unarmed civilians as a precautionary measure. Now in one sense, that's understandable. In another sense, it pretty clearly plays into the hands of Iraqi insurgents who want to drive a wedge between the broader population and their military occupiers. Meanwhile, it seems that the British troops in the south haven't made force protection nearly as high a priority as the American troops have, and as a result have gotten themselves entangled in fewer firing-on-civilian incidents. On the other hand, most reports seem to indicate that the South is less violent overall, in part because Shiite thugs and militiamen "keep the peace" and assassinate any Sunnis who get out of line (and some who don't).