It’s the spending, stupid. And not the war spending.
As Glenn’s emailer notes, it started to skyrocket right after the Democrats took over Congress in 2007. Before that we were on track to a balanced budget. The fiscal crisis would have certainly caused a spike in the deficit with reduced revenues, but absent the insane economic policies of the first two years of the Obama administration, the economy would have bounced back just as sharply as it dropped, as it does in most other recessions.