Catherine, Duchess of Cambridge speaks to soldiers as she arrives at Calgary Airport on July 7, 2011 in Calgary, Canada. (Photo by Chris Jackson/Getty Images)

Two dummy tanks being pushed along a road by German soldiers. (Photo by Hulton Archive/Getty Images). Circa 1925

A North Korean soldier throws a stone towards a photographer on the banks of the Yalu River in the North Korean town of Sinuiju, opposite the Chinese border city of Dandong October 21, 2006 in Sinuiju, Democratic People's Republic of Korea. (Photo by Cancan Chu/Getty Images)

A soldier stands guard on the aircraft park of the Pyongyang Airport on April 3, 2011 in Pyongyang, North Korea. Pyongyang is the capital city of North Korea and the population is about 2,500,000.

A Palestinian demonstrator (R) shouts at an Israeli soldier, during clashes with Israeli troops at the Qalandiya checkpoint, on June 5, 2011 between Jerusalem and the West Bank city of Ramallah. The clashes come on the 44th Anniversary of the Arab defeat in the 1967 Six Day War of the Middle East. (Photo by David Vaaknin /Getty Images)

An Aden civilian crouching in terror as British soldiers threaten him during Arabian demonstrations in Crater. (Photo by Express Newspapers/Getty Images). 1967