Linda J. Bilmes and Joseph E. Stiglitz claim in their book, "The Three Trillion Dollar War," that past estimates were much too low.
In an op-ed piece in The Washington Post Sunday, they recall when Andrew S. Natsios, head of the U.S. Agency for International Development, said U.S. taxpayers would kick in just $1.7 billion to rebuild Iraq, former Defense Secretary Donald Rumsfeld scoffed at a $50-60 billion price tag and former White House economic adviser Lawrence Lindsey weighed in at $100 billion to $200 billion.
Now, the Iraq war has become the second longest war in the history of the United States, behind Vietnam, and the second most expensive, behind only World War II, they said.
The Defense Department said as of last November it spent $396 billion on the war and the Congressional Research Service said last month the Pentagon had counted $200 billion in authorized but unused funds, the Hartford Courant reported.
But Bilmes and Stiglitz say even those figures don't take into account hidden cost such as helping future veterans and refurbishing the military. Beyond that, they say, is war's cost to the U.S. economy.
"All told, the bill for the Iraq war is likely to top $3 trillion. And that's a conservative estimate," they claim.
Notable deaths of 2014 [PHOTOS]