From 1949 to 1989, the USSR secretly conducted over 400 nuclear tests in Kazakhstan, exposing 200,000 to dangerous levels of radiation.

You already know that the United States and Russia have nuclear weapons. In total, nine countries have an estimated 16,000 warheads. Still, the U.S. and Russia own about 90 percent of the total.

http://seekernetwork.com/thishappenedhere/the-worst-nuclear-testing-you-ve-never-heard-of