How does a nation—or a community of nations—seeking to enhance their security, prevent the spread of nuclear weapons? Two approaches that have been contemplated and tried immediately come to mind— political (or diplomatic) or punitive actions. The political approach led, gradually, to building the pillars supporting the nuclear nonproliferation regime. Since the idea of a formal, structured international community has not overcome most peoples’ powerfully-held allegiance to their own nation’s sovereignty, the construction of the regime to halt or at least slow the spread of nuclear weapons drew heavily on diplomacy. The various pillars of the regime, therefore, were built over the years by separate political agreements, conventions and treaties—some multilateral, others bilateral—each dealing with specific issues related to nuclear proliferation. Separately, these mostly Cold War pacts may appear to have contributed little to rein in this awesome problem, but viewed together they may be seen as realistic pillars, when fully implemented, in the architecture of today’s nonproliferation regime. Not yet fully appreciated, the Soviet-American nuclear rivalry that dominated the first half of the twentieth century produced a convergence of common strategies designed not only to slow the spread of nuclear weapons, in general, but also to encourage non-nuclear states to forgo them altogether. Ironically, and ever so gradually, Washington and Moscow prepared the foundation of a future, global nuclear regime, albeit in piecemeal fashion, without actually solving or taming their own rivalry. It is in this sense, then, that the evolution of the various components of the Cold War nonproliferation regime has well expanded its reach.