Special operations forces also have decimated the ranks of mid-level Taliban commanders to such a degree that last year the average age of Taliban commanders dropped from 35 to 25, according to U.S. military sources.

That said, the increased military pressure on the Taliban did not bring them to the negotiating table in any meaningful way as had once been hoped. And the Taliban continue to control many rural areas of the country.

Arriving at any judgment of Petraeus' record at the CIA is complicated by the fact that he was there for only around a year and, of course, most of the activities of the CIA are secret.

Some light will be shed on the agency's recent activity when the acting director of the CIA, Michael Morell, testifies next week before the Senate Intelligence Committee about the attack on the Benghazi consulate in September that killed four Americans, including the U.S. ambassador to Libya and two men who were recently revealed to be CIA employees.

It was Petraeus who was supposed to be delivering that testimony.

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