Anthony Cordesman, adviser to Gen. McChrystal, writes in the Washington Post:

McChrystal has not announced a need for more U.S. troops, but almost every expert on the scene has talked about figures equivalent to three to eight more brigade combat teams — with nominal manning levels that could range from 2,300 to 5,000 personnel each — although much of that manpower will go to developing Afghan forces that must nearly double in size, become full partners rather than tools, and slowly take over from U.S. and NATO forces.

As I wrote at the Windy, that’s a spread of between 6900 and 40000 troops, which ought to say more about the divisions between "every expert on the scene" on the missions and purpose of that troop increase — the second of the year, if it happens — than about any consensus on the necessity for adding those troops. A spread like that is an indicator that the architects and advocates of the plus-up don’t have clear ideas about what it is the troop buildup would be meant to support. Accordingly, Cordesman defines neither "success" nor "failure" in his op-ed.