These materials include arsine and reactive materials such as arsenide salts and alloys of arsenic that decompose to produce arsine. They are first generation warfare agents that were evaluated during World War I but have never been utilized on the battlefield. These materials are commercially available but are relatively difficult to disperse. Although this class of agents is considered obsolete on the modern battlefield, arsine is

still considered a significant threat as a potential improvised weapon that could be utilized in urban warfare.