GAO undertook a review to determine the relationship between commercial spent nuclear fuel reprocessing and worldwide weapons proliferation and the adequacy of safeguards technology to detect diversions of weapons-usable material. In 1977, the President decided to indefinitely defer commercial nuclear spent fuel reprocessing in the United States because of the risks of nuclear technology and/or materials being diverted from such plants. This decision was justified on the basis that the United States can sustain its nuclear power program for the foreseeable future without reprocessing and that premature commercialization of reprocessing in the United States could encourage other nations to expand reprocessing activities. Despite the U.S. policy, many other countries continue to expand their reprocessing programs. Reprocessing, the chemical separation of usable uranium and plutonium from spent nuclear power reactor fuel, produces plutonium which can be used to construct a nuclear weapon.