Cost of U.S. wars: Around $4 trillion. Or more.

A new study attempts to put a price tag on the cost of the wars in Iraq, Afghanistan and Pakistan, as well as catalog the human toll.

The full costs of America’s wars over the past decade may never be known, but a new study this week produced estimates that, even by Washington standards, are astonishing: According to a team of researchers at Brown University, the U.S. will have spent at least $3.2 trillion and as much as $4.4 trillion, “conservatively estimated,” on both direct war appropriations and many of the long-term costs for veterans care, military benefits, and other expenses down the line. And where does all that money come from?

Per the report:

The United States paid for past wars by raising taxes and or selling war bonds. The current wars were paid for almost entirely by borrowing. This borrowing has raised the U.S. budget deficit, increased the national debt, and had other macroeconomic effects, such as raising interest rates. The U.S. must also pay interest on the borrowed money. The interest paid on Pentagon spending alone, so far (from 2001 through FY 2011) is about $185.4 billion in constant dollars.

At a news conference on Wednesday, President Obama gave war costs as one reason he wants to go forward with the drawdown of U.S. troops from Afghanistan, although he gave a much lower figure for the wars’ costs: About $1 trillion. Obama and other political leaders are counting on the savings they hope they’ll get from the reduced U.S. presence in the Middle East, although as the Brown study makes clear, Americans will be paying for the after-effects of Iraq and Afghanistan for a long time:

While we know how many US soldiers have died in the wars (just over 6000), what is startling is what we don’t know about the levels of injury and illness in those who have returned from the wars. New disability claims continue to pour into the VA, with 550,000 just through last fall. Many deaths and injuries among US contractors have not been identified.

The authors continue with their attempt to estimate the human toll:

• At least 137,000 civilians have died and more will die in Afghanistan, Iraq, and Pakistan as a result of the fighting at the hands of all parties to the conflict.

• The armed conflict in Pakistan, which the U.S. helps the Pakistani military fight by funding, equipping and training them, has taken as many lives as the conflict in neighboring Afghanistan.

• Putting together the conservative numbers of war dead, in uniform and out, brings the total to 225,000.

• Millions of people have been displaced indefinitely and are living in grossly inadequate conditions. The current number of war refugees and displaced persons — 7,800,000 — is equivalent to all of the people of Connecticut and Kentucky fleeing their homes.