环沙林（Cyclosarin）是一种有极强毒性的物质，也是一种神经毒剂。根据联合国安理会687号决议，环沙林被视为化学武器，被列为大规模杀伤性武器。

纳粹德国化学武器博士格哈德·施拉德（Gerhard Schrader）发现并合成环沙林。当时施拉德博士正在试验一系列的有机磷化合物，以切断神经系统传递去作为杀虫剂。

Cyclosarin or GF (cyclohexyl methylphosphonofluoridate) is an extremely toxic substance used as a chemical weapon. It is a member of the G-series family of nerve agents, a group of chemical weapons discovered and synthesized by a German team led by Dr. Gerhard Schrader. The major nerve gases are the G agents, sarin (GB), soman (GD), tabun (GA), and the V agents such as VX. The original agent, tabun, was discovered in Germany in 1936 in the process of work on organophosphorus insecticides. Next came sarin, soman and finally the most toxic, cyclosarin, a product of commercial insecticide laboratories prior to World War II.