President Obama spins the personnel wheel and refills the most important security and defense jobs — albeit with old faces. He has one single goal in mind: As smooth a withdrawal from Afghanistan as possible.

America is the mightiest military power on Earth. Whoever is Secretary of Defense, Chairman of the Joint Chiefs of Staff, or head of the Central Intelligence Agency has more power than his counterparts in other nations. Now, change is in the wind. Defense Secretary Bob Gates, a George W. Bush appointee kept on under Barack Obama for the sake of continuity in Iraq and Afghanistan, had long been looking to step down. Chairman of the Joint Chiefs Admiral Mullen is retiring. Obama is putting a new “war team” together.

He is not completely free to do whatever he wants. He needs advisers who have the necessary knowledge and the courage to contradict him. He must avoid choosing those qualified people simply because “it’s their turn.” That would unleash a barrage of criticism.

And he must consider the unrelated role the Senate plays in approving his choices. Personnel changes open the door for the opposition to reject any of his nominees. Anyone already serving in another capacity has a better chance of being approved.

So it comes down to the switching yard: CIA chief Leon Panetta will become Secretary of Defense, the proven General David Petraeus moves to the CIA, and General James Cartwright, formerly the Vice Chairman of the Joint Chief, moves into the top slot. So it’s a matter of keeping the old, familiar faces and giving them new jobs. They had not always agreed in the past, for example on the need to increase troop strength in Afghanistan. But the bottom line is, with their collective experience regarding Iraq they will be tasked with getting the United States out of Afghanistan without undue embarrassment.