With the world focused on the nuclear crisis in Iran, it is tempting to think that addressing this case, North Korea, and the problem of nuclear terrorism is all that matters and is what matters most. Perhaps, but if states become more willing to use their nuclear weapons to achieve military advantage, the problem of proliferation will become much more unwieldy. In this case, U.S. security will be hostage not just to North Korea, Iran, or terrorists, but to nuclear proliferation more generally, diplomatic miscalculations, and wars between a much larger number of possible players.