After the collapse of the Soviet Union in December 1991, Kazakhstan inherited 1,410 nuclear warheads. Under the leadership of President Nursultan Nazarbayev (who is still the president of Kazakhstan today) the country renounced its nuclear weapons arsenal, which had been the fourth largest in the world, and voluntarily repatriated its warhead inventory back to Russia. In later years, Kazakhstan signed START-1 , the Nuclear Non-Proliferation Treaty, and the Comprehensive Test Ban Treaty, and was instrumental in establishing the Central Asia Nuclear Weapon Free Zone along with Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan.

But Nazarbayev's most cathartic move, perhaps, was the August 29, 1991, closure of Semipalatinsk, the world's second largest nuclear weapons testing site. At the beginning of the Cold War, Stalin chose the remote corner of northeastern Kazakhstan, also known as "The Polygon," to test the first Soviet bombs. When Lavrenti Beria, the head of the KNVD secret police, selected the site, he claimed it was "uninhabited." It wasn't. Today, the area (which is not surrounded by a barrier of any kind to prevent humans and animals from roaming freely) has been called the " world's worst radiation hotspot."

"The nuclear threat strikes a deep chord within Kazakhstan. For four decades, our country was used as the backdrop for nuclear tests," wrote Nazarbayev in a 2012 op-ed for the New York Times. "Although it has been over 20 years since the last test, their devastating impact is still being felt."

On August 29, 1949, the Soviet Union conducted its first successful test of a 22-kiloton nuclear weapon, called First Lightning, at Semipalatinsk. (Although Soviet authorities knew that wind and rain would make local populations susceptible to the nuclear fallout, they disregarded the risk.) Between 1949 and 1989 the Soviet Union went on to conduct an additional 456 nuclear tests in the area --340 underground and 116 above ground -- with no regard to any environmental or humanitarian impact the tests might have. The residents of Dolon, a village located 100 kilometers northeast of Semipalatinsk, for example, were exposed to an estimated radiation dose of 140 rem during the first year alone. For comparison, the average American is exposed to a radiation dose of roughly 0.62 rem each year.

And the medical devastation wasn't isolated to that one village. According to a 2006 study from the Research Institution for Radiation Biology and Medicine at Hiroshima University, approximately 1.6 million people directly suffered from the tests, and an additional 1.2 million continue to experience the after-effects today. The health impacts of radiation exposure include genetic disease, cancer, severe birth defects, infertility, and suicide. (The 60-kilometer zone around the test site has a suicide rate that is more than four times the national average.) In fact, Japanese and Kazakh scientists determined that symptoms experienced by people exposed to nuclear radiation in the Semipalatinsk region were not dramatically different than the ones suffered by survivors of the nuclear attacks at Hiroshima and Nagasaki. In addition to the human toll, an estimated 300,000 square kilometers of land were environmentally affected by the tests.