“The occasional leakages of fissile material [from Russian nuclear weapons facilities] involve such miniscule amounts—in fractions of grams, not the kilograms necessary—that building nuclear weapons is not technologically possible.”

—William C. Martel

“It’s a matter of ‘when, rather than if’ nuclear or biological warfare material will find its way from a poorly guarded Russian research laboratory, for example, into the hands of outlaw nations, drug cartels or extremist groups.”

—Russell Shaw

The term “weapons of mass destruction” refers to weapons whose destructive capacity far surpasses that of guns or even conventional explosives. This category includes nuclear, chemical, and biological weapons. Nuclear weapons, considered by many to be the most deadly instruments of war ever devised, are highly explosive bombs whose energy comes from the fission of radioactive material. Chemical weapons, initially developed...