The First Assassination of the 21st Century

Putin's predilection for state control has one potentially positive effect in this regard: It suggests that he has a grip on nuclear safety and security. If, however, a rogue group in Russia obtained and deployed the polonium-210 on its own, it suggests that Putin's vaunted authority has limited reach. "Litvinenko's killing may be a sign that Putin is not as in control as the West believes he is," Antonenko says. "It may mean that nuclear material can still be acquired, and that elements with access to it can still act independently."

The breakup of the Soviet Union and its massive military and nuclear infrastructure loosened control over a vast and frightening arsenal. Security has improved enormously since the chaos of the early 1990s, but there are still a large number of alarming sites-ex-biological-warfare laboratories, chemical-weapon facilities-throughout the country. Russia had an estimated 44,000 tons of chemical agents (including plague, tularemia, anthrax and smallpox) at the end of the Cold War. Just 20 percent are due to be eliminated by the end of this year. "The concern is that [these materials] might be susceptible to rogue elements who could use them in pursuit of financial or other interests," Antonenko says.

It's hard to see what security services can do to stop traffic in substances that are dangerous even in microscopic doses, apart from installing ever more sophisticated detection technology and carrying out ever more invasive searches at vulnerable borders and transport hubs. And even extra measures like these won't always be successful. In January, news emerged that 100 grams of highly enriched uranium had been seized last February in Tbilisi, the capital of Georgia. The smuggler tried to sell the material to an undercover police officer posing as a representative of a terrorist organization.

At the moment, of course, former Russian spies and current Russian dissidents-not everyday citizens-are the most likely targets for exotic assassinations using polonium or other unconventional weapons. But these threats are now part of the landscape, and someone will always be prepared to spend the time and money necessary to use them. Litvinenko's murder is more than just a bizarre true-crime thriller. It's the first assassination of the 21st century, the first strike in a new world of high-tech murder.

Walter Litvinenko was in the room when his son passed away. "My son died," he said later, "and he was killed by a little nuclear bomb." The aftershocks from that explosion are still rippling through the world's security and intelligence communities. And perhaps that's just what the assassins intended. Maybe they wanted to send a message: This is a new and horrible way to die, and, in the end, no one is safe from us.

James Geary is the former Europe editor for Time magazine. He is the author of The Body Electric: An Anatomy of the New Bionic Senses and The World in a Phrase: A Brief History of the Aphorism.

Litvinenko's isn't the only unusual assassination in Russian history; for a look at some others who have fallen victim to unorthodox weapons, launch the slideshow here