The potential for terrorist use of chemical agents is a noted concern highlighted by the Tokyo sarin gas attacks of 1995. The events of September 11, 2001, increased congressional attention towards reducing the vulnerability of the United States to such unconventional attacks. The possibility that terrorist groups might obtain insecure chemical weapons led to increased scrutiny of declared Libyan chemical weapon stockpiles following the fall of the Qadhafi regime. Experts have expressed similar concerns regarding the security and use of Syrian chemical weapons, reportedly including stocks of nerve (sarin, VX) and blister (mustard gas) agents.