The 2010 TIME 100

Over the past year, all those engaged in the mission in Afghanistan have worked hard to get the "inputs" right. One of the most important inputs has been General Stan McChrystal, 55, who took command last June. I've known — and admired — Stan since we were captains together in the early 1980s. A legendary special operator and true warrior intellectual, Stan provided the forthright, thorough assessments from the field last fall that proved central to President Obama's new Afghanistan policy. Since then, he has guided the International Security Assistance Force to focus on increasing security for the people and minimizing loss of innocent civilian life while still relentlessly pursuing the Taliban. And he has sought to partner with Afghan leaders in every endeavor, recognizing that it is they who will ultimately have to take the effort forward.

Nothing about the way ahead in Afghanistan is easy. But, with his intellect, experience and sheer force of will, Stan McChrystal is the leader who can prove that the effort there is not just hard but also, in his words, "doable."

Petraeus heads the U.S. Central Command

TIME 100 Social-Networking Index: 2,886