Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. AP Explains: Novichok That Sickened Navalny a Cold War Relic Associated Press MOSCOW - Novichok, a deadly nerve agent that has left Russian opposition politician Alexei Navalny in a coma and nearly killed a former Russian spy and his daughter in 2018, was the product of a highly secretive Soviet chemical weapons program. Here is a look at the agent and the history of its development. How lethal is Novichok? Novichok, the nerve agent used in the attack that nearly killed former spy Sergei Skripal and his daughter, Yulia, in the English city of Salisbury on March 4, 2018, has been described as much deadlier than any U.S. equivalents.