The authors of the book "The $3 Trillion War" noted in a conference call on Wednesday that when they first released their findings two years ago, the estimates were widely criticized as being too high. Now, the researchers believe they may have been too low.

Joseph Stiglitz, who received the 2000 Nobel Prize for Economics, and Linda Bilmes, a public policy professor at Harvard University, said the number of veterans seeking post-combat medical care and the cost of treating those individuals is about 30 percent higher than they initially estimated. That, combined with increases in the cost of military medical care and the lagging economy, will likely push the true long-term cost of the war over the $4 trillion mark.

"This may be more of a crisis than the Medicare and Social Security problems we have looming," said House Veterans Affairs Chairman Bob Filner, D-Calif. "It rivals both in the potential impact. This is another entitlement we've committed ourselves to, and it could break the bank."

In a conference call with reporters, Bilmes said about 600,000 Iraq and Afghanistan veterans have already sought medical treatment from the Department of Veterans Affairs, and 500,000 have applied for disability benefits. That's about 30 percent higher than initial estimates for care, and could cost the department nearly $1 trillion in costs for the current wars alone.

The House Veterans Affairs Committee will hold a hearing on the costs Thursday morning. Filner said he'll use the new research to push for a "veterans trust fund" to pay for the long-term costs of war, a proposal he's already pitched to Democratic leaders in the House.

Under his plan, lawmakers would add a 10 to 15 percent surcharge on all appropriations bills, banking billions of dollars for future veterans medical costs. Reaction to the idea so far has been negative, Fliner said, because lawmakers are concerned that such a move would make the costs of war look astronomical.

Of course, Filner said, that's exactly the point. Stiglitz said history has shown the costs of treating illnesses such as post-traumatic stress disorder only increase with time, and with the country still expecting a significant presence in Afghanistan for years to come, the bills will keep piling up.