During the 2008 U.S. Democratic presidential primary, then-candidate Hillary Clinton suggested that in response to Iran’s apparent pursuit of a nuclear weapons capability, the United States “should be looking to create an umbrella of deterrence…I would make it clear to the Iranians that an attack on Israel would incur massive retaliation from the United States, but I would do the same with other countries in the region….” (Tapper 2008). Extending the nuclear umbrella, or, less colloquially, security guarantees, is intended to achieve two related goals: dissuading adversary states from developing, threatening, or using nuclear weapons by negating any offensive gains they might hope to achieve; and reassuring allies and thereby reducing their proliferation motivations.2