Secretary of Defense Cohen listens to a reporter's question during a Pentagon press briefing. Secretary of Defense William S. Cohen listens to a reporter's question during a Pentagon press briefing on NATO Operation Allied Force on April 29, 1999. Operation Allied Force is the air operation against targets in the Federal Republic of Yugoslavia. SHARE: Download: Full Size (0.02 MB) Credit: VIRIN: 173317-S-AGA42-027.jpg Photo Gallery