In December 2006 the British government released a White Paper announcing its intention to begin the process of replacing its current Trident nuclear weapons system, thereby allowing it to retain nuclear weapons well into the 2050s. In March 2008 the government released its National Security Strategy that stressed the long-term complexity, diversity and interdependence of threats to British security with a clear focus on human rights, justice and freedom. This article asks how the threat to kill tens if not hundreds of thousands of people with British nuclear weapons fits into the National Security Strategy's world view and questions the relevance of an instrument of such devastating bluntness to threats defined by complexity and interdependence. It argues that the government's case for replacing the current Trident system based on the logic of nuclear deterrence is flawed. First, Britain faces no strategic nuclear threats and the long-term post-Cold War trend in relations with Russia and China—the two nuclear-armed major powers that could conceivably threaten the UK with nuclear attack—is positive, despite current tensions with Moscow over Georgia. Second, the credibility and legitimacy of threatening nuclear destruction in response to the use of WMD by ‘rogue’ states is highly questionable and British nuclear threats offer no ‘insurance’ or guarantee of protection against future ‘rogue’ nuclear threats. Third, nuclear weapons have no role to play in deterring acts of nuclear terrorism whether state-sponsored or not. Fourth, British nuclear threats will be useless in dealing with complex future conflicts characterized by ‘hybrid’ wars and diverse and interdependent sources of insecurity. The article concludes by arguing that the government's fall-back position that it must keep nuclear weapons ‘just in case’ because the future security environment appears so uncertain, makes no sense if British nuclear threats offer no solution to the causes and symptoms of that uncertainty.