Some 80 percent of the costs of combat derive from salaries, transportation and other logistics, food, and the like, says Gordon Adams, a war expert at George Washington University in Washington. The other 20 percent is for ammunition, missiles, other weapons-related costs.
The Congressional Budget Office (CBO) took a stab at reckoning some war costs last September. The cost of deploying troops is some $14 billion. Add just over $10 billion for the first month of combat. If the war lasts longer, include an extra $8 billion for each month. After hostilities end, the cost to get the forces and their equipment home again could be $9 billion.
Not counted by the CBO are occupation costs, perhaps $1 billion to $4 billion a month, and reconstruction costs and foreign aid costs. The nonpartisan agency says it has no way to estimate such costs.
Mr. Adams describes this as a "low-end estimate."
"The historical record is littered with failed forecasts about the economic, political, and military outcomes of wars," writes William Nordhaus, an economist at Yale University in New Haven, Conn.
Factoring broader economic impacts into his estimates of the costs of an Iraqi war, Mr. Nordhaus figures the tab could range from $99 billion in the 2003-2012 period if the military and nation-building campaigns are quick and successful to $1.9 trillion if it goes badly. That big sum involves $778 billion in higher oil costs if the war destroys a large part of Iraq's oil infrastructure and $391 billion because this pushes the US economy into a slump.
In the first Gulf War, to kick Iraqi forces out of Kuwait, American allies, primarily Germany, Japan, Saudi Arabia, and Kuwait itself, covered more than 80 percent of the costs of that war. This time, the US is having difficulty rounding up supporters for its present move against Iraq.
Experts suspect European nations and Japan may be somewhat more willing to contribute to postwar humanitarian and rehabilitation costs in Iraq. Iraq's own oil revenues might eventually cover some of those costs as well.