At first, Nunn’s fears were dismissed by the White House and other members of Congress. But as the Soviet Union began to come apart, a realization soon dawned: not only nuclear weapons but also biological and chemical weapons would be scattered throughout its former territory, without oversight from any clear, centralized authority. The world’s largest stockpile of plutonium and weapons-grade uranium would also be up for grabs. And then something that today seems almost unimaginable happened. Democrats and Republicans in Congress worked closely together and passed legislation to foster greater cooperation between the Russia and the United States. Drafted by Nunn and Richard Lugar, a Republican senator from Indiana, the Soviet Threat Reduction Act became law on 12 December 1991. Two weeks later, the Soviet Union no longer existed.

The Nunn-Lugar Cooperative Threat Reduction Program sought to dismantle weapons of mass destruction in the former Soviet republics, secure fissile materials, and prevent nuclear terrorism. In the early 1990s, the situation was dire. Thousands of nuclear weapons had to be withdrawn from the field and safely locked away. The weapons could be stolen where they were deployed, during shipment, even at the main Russian storage sites, which often had rudimentary security systems. Hundreds of tons of fissile materials were even more vulnerable to theft. The Soviet Union had never conducted an inventory of its plutonium and weapons-grade uranium. Nobody knew how much there was, let alone whether any of it was missing. Nunn visited a Russian nuclear site where buckets of highly enriched uranium were being stored in an unguarded warehouse with broken windows.

The insider threat caused the greatest concern. Once among the elite of Soviet society, nuclear scientists and engineers were now struggling to get paid. The head of Chelyabinsk-70, one of the two ‘closed cities’ in the Soviet Union devoted to nuclear-weapon research, committed suicide, overwhelmed by his inability to take care of its employees. At a laboratory south of Moscow, a nuclear engineer named Leonid Smirnov stole small vials of weapons-grade uranium for months, hoping to sell it. He was caught inadvertently. While standing at a train station, Smirnov bumped into some neighbours. The neighbours were drunk and soon attracted the attention of police – who arrested all of them. When the police searched Smirnov’s bag, they were startled to find lead canisters filled with weapons-grade uranium.