In contrast, from FY 1997–2001, gross revenues exceeded expenditures and a surplus resulted. However, it has been argued that this 'balanced budget' only constituted a surplus in the public debt (or on-budget), in which the Treasury Department borrowed increased tax revenue from intragovernmental debt holdings (namely the Social Security Trust Fund), thus adding more interest on Treasury bonds. In effect, the four year 'surplus' was only in public debt holdings, while the National Debt Outstanding increased every fiscal year (the lowest deficit in FY 2000 was $17.9 Billion) However, after a combination of the dot-com bubble burst, the September 11 attacks, a dramatic increase in government spending (primarily in defense for military operations in Afghanistan and Iraq) and a $1.35 trillion tax cut, the budget returned to a deficit basis. The budget went from a $236 billion surplus in fiscal year 2000 to a $413 billion deficit in fiscal year 2004. In fiscal year 2005, the deficit began to shrink due to a sharp increase in tax revenue. By 2007, the deficit was reduced to $161 billion; less than half of what it was in 2004 and the budget appeared well on its way to balance once again.