In a highly unusual and unanticipated development, the United States government announced the end of its offensive biological weapons (BW) program on November 25, 1969. US BW stockpiles were destroyed in 1971-1972, and facilities converted. Great Britain, by then also divested of its BW program, proposed a treaty banning BW, which had been until that time always combined with chemical weapons in arms-control negotiations. The Soviet Union initially opposed this proposal, but changed its position in 1971. The USSR and the US then negotiated the final language of the treaty: it would ban the development, production, stockpiling, acquisition, retention and transfer of BW. However the US-Soviet treaty language deleted two key provisions of the British draft treaty: a ban on research, and the inclusion of on-site verification provisions. The Biological Weapons Convention (BWC) was signed on April 10, 1972 and ratified, entering into force on March 27, 1975.
Precisely at the end of 1971, the Central Committee of the Soviet Union, under Leonid Brezhnev, approved a massive expansion of the Soviet offensive BW program. From 1975 on the Soviet BW program existed in violation of the international treaty. It was a position that the USSR could maintain only through decades of deception and blatant lying. The instrumental forces in the Soviet decision-making structure that were responsible for maintaining the program during this period were a small coterie of scientists at the senior level of the Soviet Academy of Sciences, the 15th Directorate of the General Staff and senior officials of the Military Industrial Commission (VPK). If, and when, the program was definitively closed down in the decades after the dissolution of the USSR remains unknown to this day.
Why did the Soviet leadership do this? What did they intend to use BW for? Against who? In what circumstances? Why did Michael Gorbachev, despite his enormous achievements in strategic and conventional arms control in the face of opposition by the Soviet Ministry of Defense, fail to abolish the BW program? Why did an inept and disinterested Boris Yeltsin also fail to abolish the program?