Ahem - you don't seriously consider that an answer to my question, right? You're just desperately trying to distract from the fact that you cannot give an answer to my actual question, correct?

"Please, name me just one plausible explanation why russia, out of all the billions of reliable ways they could have killed the guy, they decided to try to kill him in the one way that instantly points towards them, and which is obviously extremely unreliable (since none of the victims died so far)."

True of course. But what's your point exactly?

While I do think that expelling diplomats is a bad idea, no matter who is doing it, I need to at least give the russians credit that in the case that you mentioned, the russian expelling of US diplomats was "only" an obvious retaliation response to war-monger Obama expelling russian diplomats: "You are enforcing that the number of russian diplomats is being reduced to 455? Okay, then we will enforce that the number of US diplomats is also being reduced to 455." A somewhat understandable and just response.

By the way, there's further evidence for my assumption that the main reason why those countries are expelling russian diplomats is because they feel pressured to, not because they really really want to get rid of russian diplomats:

As mentioned in the OP, Germany is expelling four russian diplomats.

But what's not so well-known is that the german government has already ruled that russia may simply send four others in exchange. A quite clever move: By joining in on the "expelling russian diplomats"-trend, they are not upsetting Washington; the NATO war-mongers can proudly claim that yet another country has decided to expell russian diplomats.
But at the very same time, by allowing that these diplomats will simply be exchanged with four others, they ensure that this is mainly just a PR stunt, and are reducing the unnecessary additional tension with russia to a minimum.

You aren't very bright if you really can't answer that yourself. Well, here is it: Russia wanted to "get caught", because it doesn't want its own agents/military personel to defect. This sends a strong message to other agents who are possibly planning to defect: there is no line that Russia won't hesitate to cross to kill them. This should be very obvious, so I don't know why you haven't figured it out.

And this nerve gas that was used is probably quite hard to handle/use, so maybe that is the reason why they haven't died yet. But from what I have read about this gas, they probably are as good as dead. Maybe it was even planned that way.

After what appears to be several assassinations by Russians in other countries I think that its obvious for other countries to take a stand against Russians period. No one wants this going on on their soil.

Guys, remember, don't feed the trolls.

See, I don't see how Russia would benefit from nuclear war.  There is a reason why there is no such thing as a nuclear war... because that is an absolute.  You don't come back from that and therefore, their is no benefit unless your desire is death and nothing else.  Our will to live is one of humanity's strongest features and a nuclear war flies in the face of that. 

Just want to point out to readers of this thread that when ArnoldRimmer frames the expelling of 755 Americans from the embassy in Russia as a tit-for-tat equivalent response because it brought the number of US personnel down to 455 which is the same as Russians in the USA, he is ignoring the fact that the USA only threw out 35 people ... versus 755. Not really equivalent. Also it was done as revenge for the sanctions and not the expulsion.

Why were the American embassy so much bigger in the first place? Don't ask me. I have little knowledge in this area—like Arnold.

Obviously you can't explain what you know nothing about. They're made guilty either way

Only Russia can know for 100% certain whether they did it or not and they've clearly stated they didn't.