Nuclear War

960 feet below ground in the Nevada desert, the US and UK conducted a subcritical test - called Krakatau - on Thursday, to view the effects of a large explosion on plutonium. Subcritical means that the explosion falls short of a nuclear chain reaction.
Krakatau subcritical experiment is being prepared to be lowered into the floor of the tunnel of the U1a Complex at the Nevada Test Site. 2/22/2006

Nevada Test Site Press Release
video from the Nevada test site
And more pictures from the Test Site of this, and other subcritical experiments.

Hiroshima peace tower reset after nuclear test: "When Minoru Hataguchi, director of the museum, pressed the reset button, the tower displayed "639," the number of days since the last nuclear experiment was conducted by the U.S. government on May 26, 2004.

Hataguchi said, "I'm angry because it's an act that tramples on the feelings of the people of Hiroshima." "

and Hiroshima, Nagasaki mayors protest nuclear weapons testing by U.S. and Britain
"Anti-nuclear groups criticize the subcritical experiments as contrary to the spirit of the 1996 Comprehensive Test Ban Treaty on nuclear arms. The U.S. has observed a moratorium on full-scale nuclear testing since 1992, but has not ratified the treaty."