Scientists have been building nuclear weapons for more than 80 years, but crafting this technology remains a challenge.

The uproar was immediate, given the sensitivity and complications of the nuclear issue and the whole concept ... weapons in defense of a nonnuclear ally. That commitment is at the heart of NATO ...

Radioactive contamination. Seizure, theft, or loss of a nuclear weapon. Accidental or unauthorized launching, firing, or use of a nuclear-capable weapon system. Public hazard, actual or implied.