Here's an interesting article following the previous Litvinenko polonium assassination which suggests Putin's invasions are connected to the poisonings.
"Putin never paid a price, and in the manner of bullies everywhere, he was emboldened when the Brits failed to respond to Litvinenko's assassination in the middle of London. That is why Putin's invasion of the small, free, and democratic Republic of Georgia was predictable. Today the Russian threat to the Ukraine is just as obvious. So the issue is not just the Republic of Georgia: It is the Ukraine, the Baltics, Eastern Europe, and even the Middle East...
Just as the Polonium assassination was designed to send a message to bully the world, the Georgia invasion used a lot of over-the-top violence -- Russia having 146 million people, and George 4-5 million. Putin went so far as to send in Cossack and Chechen irregulars, a deliberate throwback to the Czars. Back then, the Cossacks were no better than the Vikings; they killed, plundered and raped civilians. They were the battlefield scavengers of dead and wounded soldiers. Even the Prussian von Clausewitz was appalled and shamed by the Cossacks, who had no sense of military honor as he understood it.
Well, Putin has sent the Cossacks and Chechens in again after the Russian army. This is a signal to Eastern Europe where people have long memories. Russia is back to barbarism.
Under its current KGB Mafia, Moscow will act purely by Machtpolitik, unrestrained by world opinion or civilized values. Meanwhile, the Germans have put themselves at the mercy of Putin by giving him a monopoly over their natural gas supplies. Russia's Gazprom even hired the last (and worst) German Chancellor, Gerhardt Schroeder, after he passed a concessionary gas agreement with Russia through the German parliament. Europe is governed by fools or cowards, who hope to buy the friendship of the KGB Mafia in Moscow. But as soon as the Russians bare their teeth, Europe looks to the United States again for help."
http://www.americanthinker.com/articles/2008/08/barry_the_unready_and_putin_th.html
Obama's failure to respond to the Syrian red line incident told Putin he could invade Ukraine.
The US now has its Schroeder. The guy you can buy.
The Baltics and the Middle East are likely Putin's actual targets. He has delivered the poison and is watching the result.