<unk>  is an organophosphate nerve agent. It was developed in the Soviet Union under the FOLIANT program and is one of the group of compounds referred to as Novichok agents that were revealed by Vil Mirzayanov.<unk>  is reportedly slightly less potent as a nerve agent compared to some of the other compounds in the series such as<unk>  and<unk> , having similar potency to the older nerve agent VR. However it proved to be the most versatile agent as it was chemically stable and remained a volatile liquid over a wide temperature range, making it able to be used in standard chemical munitions without requiring special delivery mechanisms to be developed.
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