Ted Postol, the MIT physicist quoted in the piece, responds that US nuclear
warheads are not armed until the final rocket stage completes its powered
flight—but this is purely an engineering choice. There is no reason to
believe that a terrorist state would not arm its nuclear warheads at the moment
they are guaranteed not to fall back on that state’s own territory. Secondly,
because of the lower speeds associated with re-entry at shorter range,
short-falling warheads will in almost all circumstances have an easier re-entry
than those that go the whole way. Even if a warhead tumbled through the atmosphere,
it probably wouldn’t burn up. In fact, tumbling warheads have been identified as a
first-order threat by the missile defence programme.
