The U.S. responded the September 11 , 2001 attacks with the invasion of Afghanistan shortly thereafter . The invasion of Iraq followed in 2003 . Military expenditures approximately doubled in nominal dollars to pay for these wars , rising from around $ 300 billion in 2001 to $ 600 billion in 2008
September 11 , 2001 attacks
September 11 attacks
Economic policy of the George W. Bush administration