"Well, this is ‘need to know,’ so keep your mouth shut, but they are designed to slide on over most of our conventional ordinance. They’re made out of radioactive cobalt, and when the bomb they’re wrapped around detonates, they contaminate everything in the blast zone and quite a bit beyond."
"So they turn regular ordinance into nukes?"
"No, not exactly. The cobalt doesn’t detonate itself. It just scatters everywhere."
"Well, what? Does the radiation kill people?"
"not immediately. Cobalt jackets will not likely ever be used. They’re for a situation where the U.S. government is crumbling during a time of war, and foreign takeover is imminent. We won’t capitulate. We basically have a scorched earth policy. If we are going to lose, we arm everything with cobalt–and I mean everything; we have jackets at nearly every missile magazine in the world, on land or at sea–and contaminate the world. If we can’t have it, nobody can.
"Thus there are now whole regions that are heavily radioactive. Reports are pouring in from all three countries about soaring cancer rates, infant death rates and more. The mysterious ‘Gulf War Syndrome’ may have been caused by radiation exposure suffered by U.S. troops. So, though ‘off the books,’ the last three major U.S. attacks have in fact been nuclear in nature." ....
http://www.nypress.com/16/37/news&columns/zen.cfm