Russian agents came close to carrying out the perfect assassination on British soil when they killed Alexander Litvinenko... Security sources have disclosed that the former Russian spy would have died within hours had the poisoned tea he was given been served hot. Litvinenko, a former KGB agent who had become a critic of the government of Russia's then president, Vladimir Putin... Security sources say that during the meeting Litvinenko took just a few sips of the tea but left the remainder of the cup because it was cold. "If Litvinenko had drunk all the tea he would have been dead...