America is not strong enough, economically, to survive a war.  The problem is not the direct impact of the "Armed Forces Invoice" (much of which is in any event already committed), but the devastating indirect effect of modern war upon an advanced consumer economy.

The US economy leads the world, in the transition to a "consumer economy". That means a trading system in which the primary engine of economic growth is domestic consumption - check out "Confidence is Indivisible"  Most of the wealth-increases of the past decade have arisen in the sector of personal consumption, with US public investments (in education, health, utilities) lagging behind. 

The 2003 American economy is already quite different from the economy which fought the 1991 Gulf War. Then, domestic consumption was smaller as a percentage of national turnover (Gross Domestic Product).  Then, US foreign borrowings were relatively low - now they are high (at $500bn a year...) and the US economy cannot survive without massive foreign investment, pouring month-in month-out into American coffers. The Bush tax-cuts will reduce the Federal tax-take further, increasing the nation's reliance on borrowing.  As Americans have become richer, in the last decade, domestic savings have plummeted, placing huge reliance upon the State's backing of personal savings, and increasing the exposure of the US State to the risk of systemic collapse.  Already, the weakness of the $ is a cause for concern.  Unemployment is rising, and the re-employment process is slowing down.  If there should be any glitsch in the credit-rating of the US Federal State, and if the flood of lending into America from abroad were to falter, the US economy could come to look very weak indeed, very quickly.

Nobody knows how to "factor in" (as they say...) the effect of this growing dependency upon domestic consumption as the primary economic driver.   The Japanese economy has foundered for the last ten years, precisely because the Government has found no way of reigniting the optimism which underlies a strong propensity to consume.  There has been massive investment in public infrastructure and in the military, but that has not cheered up the depressed Japanese, and the economy has therefore remained sluggish.  The Japanese public sector is sclerotic, riddled with both complacency and corruption, and shot through with crippling cronyism.  The Japanese Police are figures of fun, seen as a cross between Inspector Clouseau and the Keystone Cops.  No wonder the Japanese are depressed.

I do not of course suggest that America is in the same case.  But there are millions of Americans who are appalled by the crude bully-boy behaviour of George Bush, and who doubt both his competence and his sanity.  They are deeply suspicious of the motives of the Republican big business cronies who constitute his power base.  If those suspicions were to grow in the American body politic, in the face of a weakening economy, the euphoria of war could turn nasty, into a depressive resentment of the incompetence of US leadership.  And if that were to happen, it would take a change of Government to retrieve the consumer optimism which alone can drive the US economy.

I suspect that the Republicans know just how great the risks are, of impoverishment by war.  That is why (in the absence of any face-saving climb-down, which would be economically preferable) they are pressing so urgently for an early, quick strike.  It's the economy, Stupid...  For the rest of us, the sensible course is to start reading the instruction-manuals on how to batten down the hatches and to survive a prolonged period of severe economic constraint.