While the Senate roils over the Levin-Warner kinda-sorta-anti-surge resolution today, one of the most important elements of the White House's Iraq plan remains unclear: the dual chain of command in place for U.S. and Iraqi soldiers.

President Bush announced on January 10 that the Iraqis would appoint an overall Baghdad commander and two subordinate commanders for Iraqi units across the nine Baghdad districts. Those commanders would be responsible for the expected 18 Army and Police brigades to be deployed throughout the capital -- who would work alongside the surged U.S. forces under the command of General David Petraeus.

Not many observers understood how this would actually work, but practically all worried about violating unity of command -- a military necessity for any successful operation. The Army's Operations Field Manual, 100-5, states clearly:

At all levels of war, employment of military forces in a manner that masses combat power toward a common objective requires unity of command and unity of effort. Unity of command means that all the forces are under one responsible commander. It requires a single commander with the requisite authority to direct all forces in pursuit of a unified purpose.

As it stands now, however, the surge possesses no such harmony. Even one of its intellectual architects, retired Army General Jack Keane, testified on January 25 that "it makes no sense to you, it makes no sense to me, but that's exactly what we're going to do, and that'll be a problem for Petraeus and his commanders to sort out."

And for his part, during his January 23 confirmation hearing, Petraeus promised to work with his subordinate commander, Lt. General Ray Odierno, to figure out how to harmonize the command structure. Sen. John Warner (R-VA), bluntly told the incoming Central Command chief, Admiral William Fallon, that unity of command "has to be clarified."

In a Salon piece last week, Mark Benjamin laid out the stakes for what to expect in Baghdad if the lack of clarity persists:

For military experts, who have long questioned the Bush strategy in Iraq, the dual command structure is just the latest in a long chain of avoidable errors. "It just shows you how flawed the whole scheme is," said retired Lt. Gen. William Odom, who was once the Army's senior intelligence officer, in an interview. Odom lamented that Iraq has been "just a bad nightmare" from the start. He said this White House continues to make mistakes that are "so painfully clear that sometimes I think I might be crazy."...

"Any kind of military operation -- but especially counterinsurgency -- only succeeds when there is a high degree of unity of command," said Bruce Hoffman, a terrorism expert at Georgetown University, who advised the Iraq Study Group. "You want to have very clear, smooth and defined lines of control. If you have dual forms of command, you have, at the start, introduced an undesirable complication. You can only have one chef stirring the pot."

Practically the only sanguine voice in the debate is that of General George Casey, the outgoing Iraq commander and one of the architects of the plan. (Albeit a reluctant one.) During Casey's hearing to become Army chief of staff on Thursday, he tried to quiet Warner's fears -- though he wasn't very successful:

SEN. WARNER: ... I'm just wondering, does this chain of command increase in any way the risk of the American GI participating in these operations?

GEN. CASEY: I don't think so. And as I said, General Odierno was out with his -- visited all the brigade commanders in Baghdad and had the conversation with them, and he reported to me this morning that he is comfortable with this arrangement. Now, is it as good as having everybody lined up working for us? No. There will be more friction than that. But I do not think that it significantly increases the risk to our forces.

Many senators diplomatically pointed out on Thursday that Casey's optimistic projections about conditions in Iraq have rarely come to pass. And as the debate over the surge heats up, this central military issue should become much more high-profile -- though, as the past three and a half years in Iraq shows, that's not to say the problem will actually get solved.