The Pentagon has asked for the resignation of General David McKiernan, the commander of U.S. and NATO forces in Afghanistan. McKiernan will likely be replaced by Lieutenant General Stanley McChrystal, a former special operations commander chosen by Defense Secretary Robert Gates. So what does the shake-up indicate about U.S. military strategy in Afghanistan? The Takeaway talks to Retired Air Force Colonel Sam Gardiner. He’s taught strategy and military operations at the National War College.