Comments by "Nigel Johnson" (@nigeljohnson9820) on "Corbyn says Johnson "misleading" public over Skripal" video.
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Si CE when did Russia have access to country of origin labeled versions of phosphorus, nitrogen, fluorine, carbon, hydrogen and oxygen. Porton Down was never going to identify the source of the poison from the chemicals alone.
The best they could hope for is to identify signature side chains associated with the method of manufacture. Even then, if the chemical structure is known, any country with a suitable chemical weapons laboratory could have made the poison.
It is more likely that the UK has access to other intelligence that indicates Russian involvement, either from electronic eavesdropping or assets on the ground (spys). This would explain why the UK is so reluctant to reveal its source. Speculating, Boris Johnson is not likely to admit that the UK has a spy inside the Kremlin, who has confirmed who gave the order for the attack.
It would be interesting to know what the UK told it's allies to convince them, it will not be just the chemical analysis of Porton Down.
( The above gives another motive for this attack, if the intention was to flush out a high level leak in the Russian government.)
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