Ex-head of FSB Nikolai Kovalev suspects Ukraine poisoned Skripal. Group of nerve agents – known Novichok – has been stored in all the ex-Soviet countries. Anyone may be involved in Skripal case, Ukraine among others.
Many competing and contradictory stories promulgated by Russian state-controlled media, the only connecting thread being to confuse their audience and exclude any possibility of Russian involvement https://euvsdisinfo.eu/disinformation-cases/?text=sergei+skripal&disinfo_issue=&date=.
The nerve agent has been identified as Novichok (which means newcomer in Russian). It is known to be more powerful than VX and was developed in Russia in the 1970s and 1980s https://www.voanews.com/a/british-prime-minister-russia-poisoning-spy/4294683.html. 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 https://edition.cnn.com/2018/03/13/europe/what-is-novichok-nerve-agent-intl/index.html, https://theconversation.com/what-we-know-about-novichok-the-newby-nerve-agents-linked-to-russia-93264.
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. http://www.consilium.europa.eu/en/press/press-releases/2018/03/19/statement-by-the-foreign-affairs-council-on-the-salisbury-attack/