(For two weeks in April, Nobel Prize-winning economist Joseph Stiglitz and Harvard professor Linda Bilmes, authors of a new book,"The Three Trillion Dollar War," fielded questions about the cost of the Iraq war and its impact on the U.S. economy. Here are some excerpts. To read more, go to: www.mcclatchydc.com/iraq/ and click on "Q&A: The Three Trillion Dollar War.")

Q: What do you think the result of this expense will be on the pocketbook of the average American family? How will this affect the value of the U.S. dollar and the cost of everyday products, food, clothing, not big screen TVs?

-- Fred Lang, Wilmington, Del.

BILMES: Right now, the average American household spends $100 per month to support the war (directly) and racks up another $100 in debt every month for long-term war costs (such as long-term medical care for wounded veterans). In addition, the war has contributed to the increase in oil prices. Oil cost $25 per barrel before we invaded Iraq, and it now costs more than $100 per barrel. In our book, we only attribute $5 to $10 of this increase directly to the Iraq war, but even this amount increased what we spend every month.

Q: While I understand your tabulation and methodology, aren't you getting a lot of shock value from simply stating the cost at $3 trillion? After all, over the 70-plus years these costs will hit the Treasury, the average annual cost is about $43 billion -- hardly as shocking. I realize these cost are front-loaded, but there are other long-term federal costs that are far larger.

-- Dave, Washington, D.C.

BILMES: We actually tried to be very conservative. You can easily support a number that is much higher, and we decided not to do that. The $3 trillion is really simple: It is just the sum of the $800 billion we will have spent by the end of 2008, the present value of a conservative estimate of health care and disability compensation for the veterans, plus the cost of ongoing fighting, replacing military equipment and paying interest on the money we borrowed. This reaches $3 trillion.

Q: Could you provide in clear "average joe" terminology what the $3 trillion figure means to people on Main Street ... ?

-- Lola Heiler, Boston

STIGLITZ: In the book, we do try to translate $3 trillion into terms that can be grasped. One way of thinking about it is that the president said America's Social Security system was broken, that, as a result, America's future was at risk. Just the cost of paying health care and disability payments for returning veterans has created an unfunded liability of more than $600 billion -- an unfunded liability comparable to some estimates of the gap in our Social Security system. To put it another way, we could put Social Security on sound financial footings for the next 50 to 75 years for a fraction of what this war has cost the economy.

In the book, we describe other ways of grasping these huge numbers -- what an hour's fighting, a day's fighting, or a month's fighting would have paid for. The president vetoed the program to provide health insurance for America's children; as a result, there are some poor children who will not get the medical care they need, impairing their future lives and productivity. The president said we could not afford it. What he was talking about was the cost of a few days of the Iraq war.

(For two weeks in April, Nobel Prize-winning economist Joseph Stiglitz and Harvard professor Linda Bilmes, authors of a new book,"The Three Trillion Dollar War," fielded questions about the cost of the Iraq war and its impact on the U.S. economy. Here are some excerpts. To read more, go to: www.mcclatchydc.com/iraq/ and click on "Q&A: The Three Trillion Dollar War.")

Q: How does the United States eventually pay off the debt and at the same time maintain world leadership with a reasonable standard of living in the future?

-- Dick Golob, Sunnyside, Wash.

BILMES: This is a good question. Recently we have not been paying off our debt -- simply borrowing more to pay off the interest. This is the equivalent of taking out a second credit card to pay off the minimum payment on the first one, and so forth. People feel that they have enjoyed a "tax cut" in recent years, but really we have just taken out a loan that we've been spending.

Personally, I believe that if our leaders had leveled with the public at the outset -- and explained that we had a choice of a "tax cut" paid for by borrowing money from China or a lower deficit and no "tax cut" -- I think the outcome would have been different. At this juncture, we will be forced to eventually raise taxes, fees, cut spending, restructure the defense budget and reduce entitlement benefits. Our children will bear much of the burden.