Why was the possible spread of Soviet biological weapons knowledge a concern after 1991?

Following the collapse of the Soviet Union in 1991, the primary concern regarding its former biological weapons program was the potential for the illicit transfer of sensitive knowledge, technical expertise, production equipment, and materials to other nations or non-state actors.1

Because the Soviet Union had maintained a massive, clandestine biological warfare program in violation of the Biological Weapons Convention, there was a significant risk that the estimated 60,000 scientists and technicians previously employed by these programs might seek employment or provide assistance to hostile entities. The international community recognized that the proliferation of such expertise and technology posed a severe threat to global security. To mitigate this, the United States and former Soviet republics collaborated through initiatives like the Cooperative Threat Reduction Program, which provided funding to help these experts transition into civilian careers, thereby preventing the dangerous dissemination of biological warfare capabilities.1