While significant progress has been made in establishing a legal barrier to the further spread of nuclear weapons, some important nations are withholding approval of this Non-Proliferation Treaty (NPT). Political factors are very significant, but agreement is made even more difficult by persistent ambiguities in technological forecasts of “how far we or they are from the bomb.” The time-lag for any crash weapon programs will not remain as extended as one might hope, because civilian technology itself is drawing states ever closer to de facto military capabilities. Yet the length of this time-lag may be crucial to the maintenance of peace if political crises emerge. Since scientists offer widely varying estimates on such time-lags, a graphical formulation is offered to reduce ambiguity. In the end, the effectiveness of International Atomic Energy Agency (IAEA) safeguards under the NPT may depend more on their symbolic and political impact than on their technology.