Why did GDP fall in Q4?
Blame lower government spending, specifically military spending. Basically, this was military drawdown.
From the report:
Real federal government consumption expenditures and gross investment decreased 15.0 percent in the fourth quarter, in contrast to an increase of 9.5 percent in the third. National defense decreased 22.2 percent, in contrast to an increase of 12.9 percent. Nondefense increased 1.4 percent, compared with an increase of 3.0 percent. Real state and local government consumption expenditures and gross investment decreased 0.7 percent, in contrast to an increase of 0.3 percent.