During the 1991 Gulf War, Iraq launched forty-three missiles at Israeli cities, not one armed with unconventional warheads, even though Saddam Hussein threatened to use weapons of mass destruction (WMD) against Israel if he were attacked by the coalition forces. Many Americans and Israelis attribute the lack of Iraqi WMD use to effective U.S. and Israeli deterrence policies. However, since “all deterrence is self-deterrence,” Israeli and U.S. deterrence policies—and their effect on Saddam’s behavior during the Gulf War—must be linked to evidence from the Iraqi side. A published collection of captured Iraqi records offers an opportunity to better understand Saddam Hussein’s perception of U.S. and Israeli deterrence signals, affording innovative insights into the reasons behind Iraq’s restraint from using weapons of mass destruction against Israeli targets during the 1991 Gulf War. This article tests a wide range of suggested hypotheses, and suggests that U.S. and Israeli deterrence played only a minimal role in dissuading Iraqi use of WMD. The article concludes with some thoughts on deterrence theory and the new challenges it faces in the Second Nuclear Age. This part examines three key terms in this discussion: ambiguous nuclear policy, existential deterrence, and the stability-instability paradox. In doing so, this article underlines the complexity of using nuclear deterrence against non-nuclear threats.