The theory most popular in the UK media at the moment is that it was Russian spies who poisoned the former military intelligence colonel, Sergei Skripal, and his daughter, Yulia. This would surprise no one. That Russian intelligence is back in the business of executing traitors has been known since the case of Alexander Litvinenko, poisoned with polonium in 2006. If the Skripal situation is part of this practice, 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 thats 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 cant admit anything without setting off a major confrontation with the UK, well likely never know if this is what happened -- and because of this, the unwritten rules of spy swaps have still been put in doubt as far as Western intelligence services are concerned.  Then theres the matter of Skripals daughter, Yulia. It was never Soviet or Russian practice to attack traitors relatives; even the 1938 case of Leon Trotskys son, Lev Sedov, is not a clear-cut assassination. Nor is there a single known case of "collateral damage" to families. The Soviet and Russian approach to retribution was always pragmatic rather than vendetta-like. All of that amounts to good reason to be skeptical of the conventional wisdom until there are real facts to support it.  That wont stop seasoned analysts from drawing preliminary conclusions: Mark Galeotti, senior research fellow at the Institute of International Relations Prague, who has studied the Russian intelligence community, wrote of "a breakdown in the old etiquette of espionage." He also pointed out that the FSB, the Russian domestic intelligence service, has been increasingly active overseas -- and that its unlikely to be bound by the old rules because it doesnt generally recognize any rules at home. 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 explanatifon 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. Putins 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 -- which is true in many areas, not just in the spy game -- would be one way of trying to force a discussion. And when a bigger goal is involved, Putins Russia and its predecessors were never hesitant to risk the lives of those loyal to them. Like the nuclear threats, though, such demonstrations of lawlessness would likely backfire. Putins problem isnt that hes not threatening enough: He is. Its that the Kremlins and its freelancers willingness to throw rules out the window reinforces the impression of the Putin regimes unreliability and makes talks appear pointless. Bloomberg View