The Soviet Union employed an estimated 50,000-60,000 nuclear experts, 65,000 bioweapons experts, and 6,000 chemical weapons experts. When the Soviet Union collapsed, many of these once-privileged scientists, engineers, and technicians became unemployed, underemployed, or unpaid. To prevent weapons experts from selling their knowledge to unfriendly states, the US government established or co-established several programs and organizations to provide scientists with civilian employment in their home countries. These "scientist redirection" and "scientist engagement" initiatives include the International Science and Technology Center, the Science and Technology Center in Ukraine, the State Department's Global Threat Reduction programs (formerly Nonproliferation of WMD Expertise), the Department of Energy's Initiatives for Proliferation Prevention and now-defunct Nuclear Cities Initiative, and CRDF.