David Petraeus must feel like Alice in Wonderland when he comes to testify before Congress. There he is in Iraq, charged to clean up the giant bowel movement the President left behind - only the bowel movement has a life of its own and is currently on a rampage, devouring people as it goes, and Petraeus is armed only with a small shovel and a crucifix. And the Iraqi Government, but in the General's SWOT analysis, they're under "W."
Then he flies across the pond, gets debriefed by the President and his handlers, they put him in a nice suit and set him off to the deliver a noncommital message to Congress. There he finds three candidates for President and all of the other Washington agenda-bots who are more prepared to lecture him than really ask him an intelligent question. Then they send him back to the fight the giant shit monster wrecking the Middle East, destroying American and Iraqi lives, and costing some $3 trillion.
Yet he must know, deep down, nothing is going to get done until there is a new administration in the White House. I am not a Petraeus fan or an apologist, but I think it's fundamentally idiotic to expect anyone in the military to take on the policy roles that are supposed to be handled by the civilian government. He knows it. That's why his testimonies are always so opaque, vague and mumbling.