TROOP VISIT U.S. Defense Secretary Chuck Hagel laughs with American service members while visiting the Kabul Military Training Center in Kabul, Afghanistan, March 10, 2013. Hagel traveled to Afghanistan on his first trip as the 24th defense secretary to visit U.S. troops, NATO leaders and Afghan counterparts. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 018218-S-BNP32-162.jpg Photo Gallery