The ultimate cost of war is, of course, the untimely death of young men and women serving their country, and of civilians who are in the wrong place at the wrong time. But war also costs in dollar terms – another $46 billion, in fact, which President Bush last week asked Congress to add to the funding package for military efforts in Iraq and Afghanistan. The cost to the taxpayer of the U.S. invasion – and now occupation – of Iraq is projected to total $690 billion by the end of next year, making it the second priciest war adjusted for inflation in U.S. history behind World War II.

President Bush argues that troops in harm’s way can be fully supported only by approval of this funding package, which will total $196 billion for the federal fiscal year that began Oct. 1. The mission, as redefined last spring, needs to be fully backed in order to succeed, he asserts. Congressional Democrats promise the request won’t see a rubber stamp, and in fact want to use it as a cudgel to thwart the president’s ongoing war plans.

The debate will be difficult to resolve because the president frames it within the context of supporting an ongoing military mission – troops out on a very dangerous limb – while Democrats see it as a clash of policies, and an opportunity to begin weaning the war from a bottomless cup of tax dollars.

As Mr. Bush enters the final year of his administration, debating his war policy is certainly germane, since a future president will inherit what remains to be done in Iraq. And part of that debate must include a financial analysis of the U.S. effort there. Our troops must be equipped, fed, housed and protected, but the return on investment needs to enter into the dialogue.

Together, the operations in Iraq and Afghanistan are expected to cost a total of $1.6 trillion. The Congressional Budget Office now reports that interest on that expenditure could run as high as $705 billion. Clearly, the Iraq occupation, as now configured, is not financially sustainable, and has serious ramifications for the U.S. and world economies.

Any well-intentioned, taxpayer-funded initiative – whether it be a war on drug abuse, crime or obesity – should be subjected to a cost-benefit question. If a nearly five-year-old program aimed at reducing teen smoking failed miserably, taxpayers would rightly oppose its continued funding. Removing troops from the Middle East linchpin that is Iraq certainly cannot be equated to a social program, but as Congress suggests changes in mission – the new strategy proposed by Sen. Susan Collins comes to mind – those approaches should be evaluated in part by their fiscal soundness.

Despite the president’s surge strategy, troop levels have not changed much since 2003, but funding has increased, so that next year, the U.S. will spend almost $1 million for each soldier, airman or Marine in the Iraq and Afghanistan operations.

It’s time to begin considering the wars we can afford.