Will May's Russian response make Britain safer?
Given there are considerably more than 50 less conspicuous ways to attempt the murder of a former spy, the Russian state and President Putin are seen by the British government to have been making a big, alarming and deliberate statement in choosing a terrifyingly toxic and internationally banned nerve agent as the weapon of choice.
That statement by the perpetrators seems to be both that anyone they perceive as an enemy can't relax anywhere, and that the laws and norms of sovereign states don't apply to them.
So the question is whether Theresa May's response today is proportionate and sensible - especially since any number of British citizens could have been collaterally killed or injured.
When I asked the PM's security minister Ben Wallace whether the prime minister was trying to punish and retaliate or protect and defend he said, "a bit of both".
Truthfully however - as most security experts would concede - there is an element of gesture in what May has done today, although simply shrugging off what she described as a "reckless and despicable act" was never an option.
All that said, there is a cloak of unreality over much that has transpired, for me at least. Her expulsion of 23 suspected Russian spies feels like a leap through a worm hole to the cold war of the 1970s and 1980s - and it'll doubtless be only hours before we know quite how many of our people are being ejected, tit-for-tat, from Moscow.
Also, I am told that within a few short days the police will take steps to seize the assets of Putin's wealthy oligarchic cronies, on the presumption that they are the ill-gotten proceeds of crime - which may be seen by the Russian president as slightly more of a provocation than welcoming home a few phoney diplomats.
British businesses with assets in Russia are anxious about how he might take revenge on them.
And among other things, UK law is being hastily changed to allow police at the border to detain those feared to be seeking entry to the UK with the malign purpose of committing "hostile state activity".
And multi-billionaire oligarchs will have their private jets grounded and searched more often - which they'll see as deeply inconsiderate.
None of this is trivial. Though to the leathery hide of Putin, it'll doubtless feel like a gnat bite.
Ben Wallace, Minister of State for Security
Which is why - as I said earlier - the more important challenge for May is to put together a coalition of countries united in their perception of Putin's Russia as unwelcome, such that it becomes frozen out of global markets, and therefore poorer, and it becomes unthinkable for celebrations of humanity like the World Cup ever to be held there.
The scale of the mountain May has to climb in forming that international coalition against Putin was shown today when the leader of Britain's main opposition party, Jeremy Corbyn, refused to condemn Putin and Moscow - because he doesn't wholly trust the evidence of the UK's security services, according to his senior adviser, and because he believes it is possible that the weapons-grade toxin was somehow stolen from a Russian state laboratory.
This absence of cross party unity even at home suggests that unless and until there is supranational corroboration of Putin's culpability, perhaps by the Organisation for the Prohibition of Chemical Weapons, Britain may in practice be standing alone against Moscow – because to date at least, the protestations of solidarity from our rich western allies, in Europe and America, are just words.