Nunn–Lugar Cooperative Threat Reduction

Cooperative Threat Reduction (CTR) is a counterproliferation program of the United States government, initially aimed at the post-Soviet states.

As the dissolution of the Soviet Union appeared imminent, the United States and their NATO allies grew concerned that Soviet weapons of mass destruction i.e. its nuclear, chemical, and biological weapons, would fall into the hands of adversarial states or terrorist groups.

The program was initiated by the Nunn–Lugar Act (Soviet Nuclear Threat Reduction Act of 1991), which was authored and cosponsored by Sens. Sam Nunn (D-GA) and Richard Lugar (R-IN). The purpose of the CTR Program was originally "to secure and dismantle weapons of mass destruction and their associated infrastructure in former Soviet Union states." By 2009, the program's remit had expanded beyond the former Soviet Union. The CTR program funds have been disbursed since 1997 by the Defense Threat Reduction Agency (DTRA).

The program facilitated, by 1996, the delivery to Russia of thousands of Soviet strategic nuclear weapons inherited by Belarus, Kazakhstan, and Ukraine, espoused in the 1992 Lisbon Protocol. In addition, the nuclear weapons delivery systems of those states, their intercontinental ballistic missiles, submarine-launched ballistic missiles, strategic bombers, and associated infrastructure were dismantled. Facilities of Russia's nuclear, biological, and chemical programs were either converted to peaceful use or given security upgrades, and 58,000 former weapons scientists were employed in peaceful work via the International Science and Technology Center.