It’s to be hoped that British investigators are getting closer to knowing what poisoned former Russian spy Sergei Skripal and his daughter in Britain. That doesn’t mean they’ll have any idea who did it.

Understandably, though, the theory most popular in the British media at the moment is that Russian spies poisoned the former military intelligence colonel and his daughter, Yulia.

If that’s what happened, two things are striking about it because they would suggest that Russia has blown up unwritten spy game rules from which it has repeatedly benefited: first, that Skripal had been “off the board” after being tried, convicted and traded to the UK and, second, that his daughter had apparently been targeted along with him.

In 2010, the ex-colonel was one of four people who came to the West as part of a widely covered spy swap, in which the US released 10 Russian “sleeper agents.” There had been at least a dozen spy exchanges between Western countries and the Soviet Union and its satellites during the Cold War, but this was the first publicly announced one in the Vladimir Putin era.

None of the people traded to the West in these swaps has ever been assassinated. The possibility of a swap is a perk that makes it marginally worthwhile to spy for a foreign power.

The money paid to spies or the moral satisfaction of working against a hated regime is never enough to compensate for the dreadful risk of this work; not even the implicit promise that the side you work for will take care of you will tip the scale if you have to look over your shoulder for the rest of your life.

A swap, however, has been a guarantee of peaceful retirement. If that’s no longer the case, this raises the stakes for spies — and makes swaps pointless.

Having resumed the Cold War-era practice of swaps, why would Putin or his spy chiefs want to ruin it by approving the assassination of a former spy who had served part of his sentence in a Russian jail and was then put out to pasture in the UK?

One answer could be that Skripal perhaps continued working for British intelligence after he was traded. But since the Russian government now can’t admit anything without setting off a major confrontation with the UK, we’ll likely never know if this is what happened — so the unwritten rules of spy swaps have still been put in doubt as far as Western intelligence services are concerned.

Then there’s the matter of Skripal’s daughter, Yulia. It was never Soviet or Russian practice to attack traitors’ relatives; even the 1938 case of Leon Trotsky’s son, Lev Sedov, is not a clear-cut assassination. Nor is there a single known case of “collateral damage” to families.

Whether or not the attack was sanctioned by the Kremlin, or reflects a new culture in the intelligence services, the assassination attempt sends a clear signal to Russians who work, or who have worked, for Western intelligence services: There is no arrangement they can make to stop looking over their shoulder.

This is a powerful message, and its flip side is that anyone working clandestinely for Russia can also expect harsher treatment, if not poison in their drinks and attacks on their kin. Would the Kremlin risk such reciprocation — and the almost-inevitable UK response — just to take out a retired spy? If not, the Kremlin had better hope an alternative explanation surfaces quickly and that, if rogue elements were involved, they are punished.

And yet the answer may be yes, for the same reasons that Putin recently devoted a major speech to threatening the US with a set of newly developed nuclear superweapons. Putin’s stated goal is to be heard by the West and to force negotiations on security issues. Showing that there are no rules of engagement for this iteration of the Cold War would be one way of trying to force a discussion.

Such demonstrations of lawlessness would likely backfire. Putin’s problem isn’t that he’s not threatening enough: He is. It’s that the Kremlin’s and its freelancers’ willingness to throw rules out the window reinforces the impression of the Putin regime’s unreliability and makes talks appear pointless.

There will hopefully be more clarity to come. In the meantime, perhaps the best thing the West can do is fortify itself against further attacks.

This means stepping up the protection of Putin foes, especially those who could be viewed as traitors by the regime, keeping a close watch on Moscow’s formal representatives and working to reduce any informal influence it might have. Whatever investigators uncover, the harder task will be responding to it.

© 2018, Bloomberg View