Indiana Sen. Richard Lugar, left, Secretary of Defense Leon E. Panetta, center, and former Georgia Sen. Sam Nunn pose for photographs during a ceremony honoring the senators for their work to help denuclearize countries after the fall of the Soviet Union during a ceremony at the National Defense University in Washington, D.C., on Dec. 3, 2012. Panetta earlier presented Lugar and Nunn the Defense Department’s highest civilian honor, the Distinguished Public Service Award. The Cooperative Threat Reduction Program, established in 1991 as part of the Nunn-Lugar Act, is a critical part of the U.S. approach to reducing the threat of proliferation of weapons of mass destruction and related materials.