This pair of papers examines the two nuclear superpowers that together possess more than 95 percent of the world's nuclear weapons. Dmitri Trenin, director of the Carnegie Moscow Center, evaluates the odds of Russia forging its increasing reliance on its nuclear arsenal in the context of multilateral disarmament. The Stimson Center's Barry Blechman, Alex Bollfrass, and Frank Valliere trace the evolution of the United States as the first nuclear-armed power to advocate for global zero.