Political theorists had vigorous debates about nuclear weapons in the 1980s but have been largely silent about them recently. This article seeks to reopen those discussions. It evaluates the main justifications for nuclear proliferation since 1945: arguments from consistency, nationalism, democratic legitimacy, self-defense, peaceful effects, and supreme emergency. Most of these arguments are badly flawed, as are the arguments for retaining the nuclear arsenals of many of the established nuclear powers. Instead, this article proposes a first cut at a stringent (...) standard for judging the acquisition of strategic nuclear weapons, drawing on jus ad bellum and jus in bello principles. (shrink)