I think that most of this $8.5 billion might have been spend on secret missions and assignments, just like the recent Kiev intervention. This spending can't be made public, as it will anger a lot many of the allies of the United States (The US regularly back stab its allies, although it tries its best to pull things under the carpet). 
It clearly says Trillion, not billion. $8.5 Billion = $8,500,000,000
$8.5 Trillion = $8,500,000,000,000
The difference is huge. If it were $8.5 Billion as you've said, then it wouldn't be much of a deal for country the size of the USA. The daily budget is just over $10B. http://demonocracy.info/infographics/usa/us_deficit/us_deficit.html
$8.5 Trillion dollars is really a lot of money.
Here you can find a visualization
http://demonocracy.info/infographics/usa/us_debt/us_debt.html