Governments are concerned about the dangers posed by ballistic missiles. However, there is almost no theoretical or empirical scholarship on ballistic missiles. This article presents and tests the conventional wisdom that the spread of ballistic missiles makes conflict more likely. Original data on ballistic missiles and on crisis initiation is collected, and analysis using a variety of statistical models is conducted. It is found that among all directed dyads from 1946 to 2007, potential challengers possessing ballistic missiles are significantly more likely to initiate international crises. Further, potential targets armed with ballistic missiles are significantly less likely to be challenged. Crises are less likely to escalate when targets are armed with missiles. The results are obtained after accounting for several control variables. Analysis reveals that the findings are not affected by possible endogeneity bias. The analysis also reveals complex interactive effects between ballistic missiles and nuclear weapons on the onset of international crises.