EXECUTIVE SUMMARY: A peculiar chronology can be spotted when examining the milestones marking the history of the development and use of persistent nerve agents around the world. Coincidentally or otherwise, Iran, North Korea, and Russia have all been mentioned in the context of nerve agents in recent years.
The category of chemical warfare agents known as nerve agents has two sub-categories: volatile (non-persistent) and persistent nerve agents. The first is typically represented by sarin, a toxicant that was used in the Tokyo subway sabotage (conducted by the Japanese movement Aum Shinrikyo in 1995), during the Iraq-Iran War (when it was used by the Iraqi army), and during the Syrian Civil War (when it was used by the Assad regime).
Persistent nerve agents typically consist of VX and the Novichok group. In the battlefield, persistent nerve agents have been used only once: in the 1980s, Cuba deployed VX against Angolan insurgents during the Angolan Civil War.
Much attention has thus been drawn towards the notorious Novichok poisonings that occurred not long ago in Britain. For the purpose of killing specific individuals, persistent nerve agents like Novichok are more effective than volatile agents in that they adhere to the victim (to simplify somewhat).