The Guardian article I linked to above, summarised it thus:
"Now, there are two plausible explanations for how the poisoning story went down, and neither paints a particularly optimistic picture. If it’s indeed Vladimir Putin’s
deep hatred of turncoats that prompted him to authorise the Skripal hit, as the New York Times alleges, then he critically lacks any strategic foresight and has let personal animus take precedence over Russia’s immediate and long-term interests. If he truly didn’t anticipate all the sanctions, diplomatic expulsions and a newly galvanised global opposition to Russia — or he just didn’t care — then engaging with him in any sensible way might be simply impossible. We already know that the man
gets high on his own fake news supply and is an ardent believer in some pretty kooky conspiracy theories.
If Putin didn’t authorise the operation, this makes the matters even worse, both for Russia and for the world. Because that would mean that Putin doesn’t control his own security apparatus, whose members go rogue on ever more reckless vengeance missions at home and abroad. "
The 2nd option is beginning to look increasingly likely.