Kim Jong-un's brother allegedly was killed using a nerve agent:
Now a former Russian spy and his daughter allegedly have been killed in a similar fashion:
In the Korean case, we soon were told the alleged nerve agent was VX. In the Russian case, we have yet to learn what was used.
I have three comments on all this:
(1) North Korea has a long history of collaboration with the USSR and Russia. Neither of those countries used VX; but they did (do) possess an analog known as Substance 33.
(2) Might the slowness to tell us what happened to the Russian spy mean the agent used was a Novichok variant?
(3) It is quite likely the US, UK, Israel, and others in the West are capable of making Novichok, so if it turns out to be what was used in the most recent attack DO NOT automatically assume it was the Russians who committed this latest crime.
You can read more about Novichok here:
By the way, the US had the option of demanding that Novichok be added to the Chemical Weapons Convention but failed to do so. Is this because Uncle Sam and his buddies wanted the ability to "legally" make it themselves?