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On March 14, UK Prime Minister Theresa May announced the expulsion of 23 Russian diplomats in response to a March 4 "military grade" nerve agent attack that poisoned former Russian spy Sergei Skripal and his daughter, as well as a police detective who visited his home in Salisbury, England. Dozens of other people may have also been exposed to the nerve agent in a pub and restaurant the Skripals visited before they were found unconscious on a bench.

UK law enforcement and security officials have said that the nerve agent used in the attack was one of a series of chemical weapons developed by the Soviet Union during the height of the Cold War known as Novichok, or "newcomer." Today, the leaders of the UK, the US, France, and Germany issued a joint statement condemning Russia for the attack, stating that it "constitutes the first offensive use of a nerve agent in Europe since the Second World War," and demanding full disclosure of the Novichok program by Russia to the Organization for the Prohibition of Chemical Weapons. NATO Secretary-General Jens Stoltenberg offered "practical support" if May's government requests it, saying the attack "has no place in a civilized world." And further diplomatic action from France and Germany against Russia is expected.

Russia has denied any role in the attack, while at the same time using state media to suggest the attack was a justified strike at a traitor. Sergei Skripal was a double agent for the UK's intelligence services who was arrested by Russia in 2004. He was released as part of a spy swap that included the return of Anna Chapman and nine other "illegal" Russian Foreign Intelligence Service (SVR) sleeper agents arrested in the US in 2010.

How Novichok works

Novichok agents, which were designed to be undetectable, may use a combination of two otherwise harmless chemicals. They were developed as a way to get around the Chemical Weapons Convention, which banned the stockpiling of chemical weapons and their precursors. Like other nerve agents and some components of cobra venom, Novichok agents inhibit cholinesterase enzymes, which are essential to the functioning of neurons.

Suppression of cholinesterase can cause nerve impulses to be continuously transmitted, preventing muscle contractions from stopping—causing muscle spasms and, eventually, death. According to information provided by a dissident Soviet scientist, Novichok is believed to be eight to ten times more powerful than VX or sarin gas. While areas directly exposed to the agent are affected almost immediately, it's believed that the full effects of the agent could be delayed up to 18 hours after exposure, according to the authors of Responding to Terrorism: A Medical Handbook. Even with the application of antidotes, these agents can result in permanent damage to victims.

Last September, Russian President Vladimir Putin claimed that all of Russia's chemical weapons stockpiles were gone. According to the Associated Press, Russian chemical weapons expert Igor Nikulun claimed all of Russia's Novichok agents were destroyed by the US during the Nunn-Lugar Cooperative Threat Reduction Program in the 1990s and that much of the equipment for producing the agents was brought back to the US. (That program was focused on nuclear proliferation risks).

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