The Bush Administration is demanding that other countries tighten up on proliferation of nuclear materials and technology. But at the same time, the US is doing a poor job of maintaining its own arsenal of nuclear weapons. Six nuclear missiles were flown across the continental United States by mistake. Nuclear missile nose-cones were mistakenly shipped to Taiwan. After those incidents, the Secretary of the Air Force and its top civilian official were fired by Defense Secretary Robert Gates. Now another embarrassment has surfaced: hundreds, perhaps thousands, of nuclear missile components have turned up missing.