They were no-shows in Iraq, but tons of chemical weapons are stoking fears and costing billions to clean up elsewhere in the world - from concrete "igloos" in Oregon, to the Panama rainforest, to the highlands of China, where Japanese war leftovers reportedly have killed hundreds.
"Threat reduction," a historic U.S.-Russian effort that has ballooned to a $1 billion-a-year enterprise, is steadily locking down more of this country's "loose nukes," the warheads and bomb material whose security deteriorated in the disarray after the Soviet Union's collapse.
The current explosive impasse between India and Pakistan over divided Kashmir is more than a showdown between two neighbors' massed armies. It has a nuclear dimension, too, and that has the world worried. Those who follow the Asian powers' emerging strategies doubt they will come to nuclear blows. But ultimate weapons force consideration of ultimate scenarios, and of miscalculation even by the coolest heads.