Putin's nerve agent miscalculation
...The attack on the former spy will also make it difficult for Putin to engage in swaps of his own spies caught in the West in the future. Why give the Russians back one of their assets if they are going to kill the ones coming this way in the bargain?
Timing matters greatly here.
After all, Russia is about to host the World Cup and Vladimir Putin wants to show off Russia as a place to visit and invest. Instead, the diplomatic expulsions have drawn international media attention to Putin's decision to spread an exceptionally toxic nerve agent compound around a small British town.
In turn, the Russian leader's assassination antics have given him an utter "blowback" failure. In intelligence circles, blowback refers to an operation in which a mission causes far more harm to those carrying it out than those they targeted.
Consider that Skripal and his daughter weren't killed (although he might still die), and Putin has made himself more of an international pariah than ever before.
The exigent question now is what follows? I think one of two things.
Either Putin will escalate further by attempting to kill another defector or, perhaps, by escalating his harassment of U.S. persons in Russia. Alternatively, he may back off and hope to get the World Cup concluded without further problems.
If he chooses the latter, then we can move on (although the British must crack down on Russian organized crime-Kremlin money in London).
That said, if Putin does decide to escalate, the U.S. should play him at his own game....