How Big a Troop Surge?

Defense Secretary Robert Gates is taking issue with estimates from the nonpartisan Congressional Budget Office that the cost of the surge will be much higher than anticipated and that the surge itself will require an additional 28,000 troops to support the 21,500 extra combat troops already headed there.

The Congressional Budget Office's analysis was released yesterday by Democratic lawmakers who commissioned the study. The CBO estimated that the troop increase could cost about $13 billion for a four-month surge and that 21,500 combat troops might need as many as 28,000 additional support troops. The CBO based its estimates on an analysis of past and current Pentagon deployments.

"The CBO study, I think, dramatically overstates both the cost and the personnel," Gates said at a Pentagon news conference today.

Referring to the extra support troops, Gates said, "We think that number -- it's not settled for sure right now -- but that number looks, right now, like it will be about 10 percent to 15 percent of the number that CBO cited."

That would be in the range of 2,800 to 4,200 additional troops. An Army official tells ABCNEWS.com that initial estimates say that 3,000 additional support troops may be needed to support the extra combat troops.

Gates did not provide a cost estimate for the troop increase, but spokesman Bryan Whitman later said the Pentagon still estimates the cost of the surge as being $5.6 billion through the end of this fiscal year, which ends Sept. 30.

Gates has publicly stated his belief that the surge will last only a matter of months rather than year. "Those of us involved in the process thought of it in terms of months, rather than 18 months or two years. The CBO estimate was based on the surge of troops lasting through the end of fiscal year 2009."

In the end, the number of extra support troops may be a wash anyway. That is because the 4,000 Marines who saw their tour of duty extended in Al Anbar province by two to three months will begin coming home around the same time that the five-brigade surge into Baghdad gets into full gear.