Terrorists want many witnesses, not many dead. Terrorists use violence to achieve ends other than murder for murder's sake. Using the weapons they have had for decades, terrorists could have killed in greater quantities had that been their sole objective. Not doing so is a choice, not a technical limitation. Terrorists are governed by self-imposed constraints, including their own moral qualms and their concerns about cohesion. Terrorists worry about alienating their perceived supporters. Although terrorists want to provoke fear and alarm, they do not want to provoke too great a public backlash. Fear of unleashing strong public support for government crackdowns is another deterrent for extreme terrorist violence. Although there have been recent reports of plutonium and highly enriched uranium being smuggled out of Russia, there is no evidence that any terrorist group has sought to acquire nuclear material or even that terrorists have seriously contemplated using nuclear weapons. Lesser acts of nuclear terrorism, such as the use of radioactive materials as a contaminant or the fabrication of potentially alarming nuclear hoaxes may be more plausible.