Vladimir Putin's warning about Russia's nuclear readiness has sparked global concern. With the world's largest nuclear warhead stockpile at about 5,580 warheads, Russia's nuclear policy allows their use in response to attacks using nuclear or other mass destruction weapons, or when conventional weapons threaten Russia's existence. While Russia has not tested nuclear weapons since 1991, Putin's signing a law to withdraw from the Comprehensive Nuclear Test Ban Treaty indicates a willingness to resume testing. The president holds sole authority over nuclear weapon use, facilitated by the "Cheget" briefcase, a communication tool for nuclear launch orders.