Polonium: The Terrorists' Perfect WMD? (updated)

"The disclosure that "seven workers at the Millennium Hotel, where former KGB agent Alexander Litvinenko met a contact on the day he fell ill, have tested positive for 'low levels' of polonium" further expands the serious consequences of the investigation into Litvinenko's murder. (UPDATE: A former KGB who met with Litvinenko in London has fallen into a coma from contact with "a radioactive substance.") A CTB reader who graduated from MIT wrote me recently with the following information on polonium:"
CT Blog

`I would characterize it as an act of war, not a terrorist attack. Until I know how the polonium was introduced, and how much was introduced, and of course who did it, I would consider it a grave violation of national security by an enemy state. If in fact this material somehow got out and into the hands of non state actors, then I still see a reason to have some serious talks with the Russians about their current control regime.