As reported by the Washington Post.
The Nevada National Security Site, formerly called the Nevada Test Site, is just 65 miles northwest of Las Vegas. It is located on Western Shoshone Indian land, as affirmed by the Treaty of Ruby Valley of 1863, as signed by the U.S. government. The Western Shoshone have led the resistance to nuclear weapons testing, and radioactive waste dumping (Yucca Mountain), on their lands, for many decades.
Despite this highest law of the land, equal in stature to the U.S. Constitution itself, the U.S. has detonated nuclear wepaons there since 1951. For a dozen years, testing took place at the surface, with large-scale radioactive fallout downwind, across North America. This caused large-scale harm to human health and the planet.
After the Atmospheric Test Ban Treaty went into effect, the testing moved underground. But the National Security Archives revealed earlier this decade, that around one-third of the underground tests leaked or vented to the atmosphere. This was kept largely secret from the American people, although some leaks were so big, the truth did not take long to come out, despite efforts to keep it secret. In the case of the "Mighty Oak" underground test in April 1986, large-scale hazardous radioactivity releases to the environment took place. The Department of Energy tried to mask its intentional venting releases as having been caused by the Chernobyl nuclear power catastrophe in the U.S.S.R., but Dr. Rosalie Bertell outed the subterfuge.
After a moratorium on full-scale testing was declared in September 1992, sub-critical testing has continued at the NTS/NNSS. Sub-critical testing involves conventional explosives, packed with plutonium. The data from the sub-critical tests is fed into supercomputers; nuclear weapons designs can be "advanced" that way, even without full-scale testing.
In 2006, a very large-scale conventional explosion, codenamed "Divine Strake," was proposed at the NTS/NNSS. The data collected would have been used to "advance" (calibrate) bunker buster nuclear weaponry. The test was a thinly veiled Bush/Cheney administration threat against Iran's nuclear facilities. But an environmental coalition -- including Toledo attorney Terry Lodge, and Michael Keegan of Don't Waste Michigan and Coalition for a Nuclear-Free Great Lakes -- intervened, successfully challenging the Department of Energy/National Nuclear Security Agency's plans. The coalition showed that the National Environmental Policy Act had been violated, due to the large environmental and human health impacts downwind, that would be caused by stirring up so much radioactive contamination from past nuclear tests. The "Divine Strake" test in Nevada was cancelled; and everywhere else in the country where DOE/NNSA later attempted to carry out the test, it was also successfully blocked.