The problem with almost any unilateral action taken by Theresa May today against Russia is that President Putin will swat it away with tit-for-tat retaliations; he will neither admit culpability or show greater respect for the laws and mores of other countries.
If she expels 30 of his diplomats, he’ll presumably exile 40 of the UK’s.
If the prime minister were to ask Ofcom to review Russia Today’s licence to broadcast (which would perhaps be slightly eccentric for a country that champions freedom of expression until it becomes incitement to hate) he’ll doubtless force countless British journalists to go home.
And in the unthinkable case that she talks about launching a cyber-attack on Russia - unthinkable because she would be legitimising such attacks by rogue states on us - I shudder to contemplate what Russia’s response would be.
Doubtless she will today announce visa bans and asset freezes on putative Russian undesirables. And some Russian officials will be sent packing.
I would be surprised if her immediate and unilateral response to the poisoning is much more than that.
Because the penny has dropped in government that what would be much more effective is a multi-lateral response - solidarity against Russia’s overseas adventurism by the rich developed countries, notably France, Germany and the US.
If the evidence shows that Putin’s Russia is a rogue state, then Putin may only think twice about committing acts of aggression on foreign soil if the economic costs of so doing are greater than the UK solo can impose.
Even the mooted boycott of the World Cup would be laughable if by England alone - though would be a humiliation to Russia if it involved a significant number of teams.
But the challenge with the multi-lateral response is that the American president does not seem to have the notion of “international solidarity” in his lexicon. His America First is synonymous with “my way, or no way”.
Rarely has the so-called and slightly mythical “special relationship” between Britain and America seemed more important - and rarely has it been so elusive.