In this dissertation I investigate different decisions concerning nuclear weapons. I do this by focusing on what I call traumatic events: high-impact external shocks that affect a state's perception of its position in the international system in a negative direction. I integrate the theoretical models of nuclear proliferation and nuclear conflict with cognitive to investigate how traumatic events impact certain decisions. I dedicate one article to one type of decision. In the first article, I investigate the very decision to pursue nuclear weapons. In the second article, I investigate deterrence failure and the decision to start militarized conflict, contrasting nuclear dyads (where both states have nuclear weapons) with other dyads. Finally, in the third article, I investigate decisions to increase military burdens, also contrasting how those differ between nuclear and non-nuclear weapons states.