State Sponsored Terror
When GW took office, Russia was still crippled by its weak economy. High oil prices, and Russia's control of much of the World's natural gas, have changed that. So has Bush's decision to fritter away American power, lives, and money in Iraq.
Polonium 210 looks like a good way of saying: "This message approved by the FSB." According to Wikipedia, Polonium 210 is about 250 billion times as toxic as cyanide per unit mass.