In the months leading up to the March 19, 2003, invasion, President George W. Bush and his top aides had sold the war as both necessary and relatively cheap. But the past decade has shown conclusively that it was neither, according to a new report.

The war killed at least 190,000 people, including nearly 4,500 American troops, plus 3,400 U.S. civilian contractors, according to the "Costs of War" project at Brown University's Watson Institute for International Studies.

In addition, multiple deployments over the past decade have brought home more than 30,000 American troops dealing with a variety of serious injuries, including traumatic brain injury, or TBI, and post-traumatic stress disorder, or PTSD. At least another 30,000 American troops are estimated to suffer some type of mental illness, according to the Archives of Internal Medicine.

More than 70 percent -- or 135,000 -- of Iraq war deaths were civilians. It's estimated that at least three times that number died indirectly from the war, because of increased vulnerability to injury, disease and criminal violence, according to the report.

The war will cost U.S. taxpayers at least $2.2 trillion. But because it was paid for on the national credit card, the true cost through 2053 will be closer to $4 trillion, according to the report.

Finally, the United States spent about $60 billion on the reconstruction of Iraq, but at least $8 billion of that -- and possibly more -- disappeared because of massive fraud, waste and corruption, according to the Special Inspector General for Iraq Reconstruction.

One of the biggest legacies of America's decision to invade Iraq is that Iraq and Iran, its much-larger eastern neighbor, are today friends, an alliance based on religion -- both are majority Shiite Muslim nations -- and their mutual hostility to the United States.

This picture contrasts with the situation before the invasion. Under dictator Saddam Hussein, Iraq was Iran's fierce adversary, a counterweight to Iran's regional ambitions, according to Michael Boyle, an assistant professor of political science at LaSalle University, in Philadelphia.

The Iraq-Iran alliance, Boyle said, "is a great example of how you think you're going to do something when you start a war and it often turns out the way you think it will."