The following discussion focuses on the question of whether a terrorist organization or a threshold state could make use of plutonium recovered from light‐water‐reactor fuel to construct a nuclear explosive device having a significantly damaging yield. Questions persist in some nonproliferation policy circles as to whether a bomb could be made from reactor‐grade plutonium of high burn‐up, and if so, whether the task would be too difficult for a threshold state or terrorist group to consider. Although the information relevant to these questions is in the public domain, and has been for a considerable time, it is assembled here for use by policy makers and members of the public who are concerned about preventing the spread of nuclear explosives.