[Schrodinger's Cat]

Yes, most of the deaths were due to military actions, but concern about infant mortality rates was also a vital component of the study:

The Coalition Provisional Authority and the Iraqi Ministry of
Health have identified the halving of infant mortality as a major objective.

The paper goes on to discuss this in further sections, so death by violence was NOT the only thing the researchers were looking at.

They also state that violent deaths were mostly due to air strikes, so, once again, this is not some diatribe about evil US soldiers gunning down helpless civilians on the street. It is about the failure of the US military command to use its so-called precision bombing techniques:

Violence accounted for most of the excess deaths and air strikes from coalition forces accounted for most violent deaths. We have shown that collection of public-health information is possible even during periods of extreme violence.

The authors practically request that the US military follow up on their preliminary study:

Our results need further verification and should lead to changes to reduce noncombatant deaths from air strikes.

If a couple of University professors with limited funding were able to carry out a study valid enough to be published in a highly respected, peer-reviewed scientific journal; surely, the DOD with its much greater access to funding and materials could do the same and end the controversy one way or the other. Why don't they?