THUMB WRESTLE Defense Secretary Chuck Hagel, left, thumb wrestles Frederick Downs Jr., a fellow Vietnam War veteran who Hagel has known for more than 30 years, during a prosthetics presentation at the Pentagon, April 22, 2014. The Defense Advanced Research Projects Agency, or DARPA, also showcased the Atlas robot, long-range anti-ship missile and persistent close air support. SHARE: Download: Full Size (0.06 MB) Credit: VIRIN: 338605-Z-CQJ83-703.jpg Photo Gallery