On July 2, the Department of Energy (DOE) conducted the first in a series of "subcritical" experiments deep underground at the Nevada Test Site. Although these experiments involve the use of nuclear weapon materials (including plutonium) and high explosives, these components are not in a potential weapons configuration and cannot generate a nuclear yield. DOE maintains that the experiments, which will produce data on the behavior of plutonium under extreme conditions of temperature and pressure, are an "essential component" of its science-based stockpile stewardship program intended to ensure the safety and reliability of the U.S. nuclear arsenal under the Comprehensive Test Ban (CTB) Treaty. DOE plans to conduct one more subcritical experiment this fall and four in 1998.
Though the July 2 experiment, code-named "Rebound," drew some international and domestic criticism, most governments (Iran was the notable exception) refrained from characterizing the experiment as a nuclear weapons test and a violation of the CTB Treaty. Chinese Foreign Ministry spokesman Tang Guoqiang said July 3 Beijing "will closely follow this situation" and urged all states to "faithfully fulfill their commitments" under the treaty. That same day, State Department spokesman Nicholas Burns replied that the subcritical experiments are consistent with the CTB Treaty because they are not nuclear tests and that the Chinese "ought to get their physics right."
Earlier, in a June 20 letter to President Bill Clinton, 44 members of the House of Representatives urged the administration to cancel the experiments, claiming that they are not necessary to ensure the safety and reliability of the U.S. nuclear stockpile and "could severely damage global entry-into-force of the [CTB]."