Knowledgeable observers have long suggested that this was the case, but an official Congressional Budget Office analysis agrees that the escalation in Iraq will be larger than officials have claimed. The issue is that when the President talks about 21,500 extra combat troops, you have to send additional support units. Those extra combat units need truck drivers, military police, headquarters staff, communications experts, engineers, intelligence officers, and medical assistance. To support the combat units being deployed, you have to send additional non-combat units (which will still encounter dangerous conditions, naturally).
The nonpartisan CBO considered two scenarios:
In one scenario, CBO assumed that additional support troops would be deployed in the same proportion to combat troops that currently exists in Iraq. That approach would require about 28,000 support troops in addition to the 20,000 combat troops—a total of 48,000. CBO also presents an alternative scenario that would include a smaller number of support personnel—about 3,000 per combat brigade—totaling about 15,000 support personnel and bringing the total additional forces to about 35,000.
For comparison, there are about 140,000 troops currently deployed to Iraq, so we are talking about a 30% increase. Those additional forces will be deployed into the most dangerous parts of Iraq, giving them much higher casualty rates, one presumes. What we will get in exchange for that sacrifice is not at all clear.