Prime Minister Theresa May lied when she claimed that the toxic substance used in the Skripal poisoning case was manufactured in Russia: Porton Down has later denied her claim.
Novichok is known to be more powerful than VX and was developed in Russia in the 1970s and 1980s. It's so unusual, that very few scientists outside of Russia have any real experience in dealing with it and no country outside of Russia is known to have developed the substance. See reports by CNN, BBC, the Guardian.
In its statement, the European Union expressed shock at the offensive use of any military-grade nerve agent, of a type developed by Russia, for the first time on European soil in over 70 years.