The Department of Energy (DOE) conducted its third subcritical experiment, code-named "Stagecoach," at the Nevada Test Site on March 25. Although the experiments utilize fissile materials, they do not generate any nuclear yield and are thus compliant with the Comprehensive Test Ban (CTB) Treaty. DOE contends that the subcritical experiments are an integral component of its Stockpile Stewardship and Management Program, which is designed to ensure the safety and reliability of the U.S. nuclear arsenal in the absence of nuclear testing. Critics, on the other hand, have argued that the subcritical experiments are unnecessary and that the United States should institute greater transparency measures in order to provide assurances that these activities do not circumvent the CTB Treaty.
The first two experiments were conducted July 2 and September 18, 1997. DOE plans to conduct at least one more experiment this year.