Counterterrorism investigations are based on the fundamental duty of government to protect the public against terrorism and criminal violence which may be intended to destroy or manipulate the constitutional system. The approach taken in these investigations is responsive to the need to both prevent incidents where possible and to react effectively after incidents occur. The Counterterrorism Section (CTS) at FBI headquarters in Washington, D.C. provides program direction and management to all FBI counterterrorism investigations. Within each field division, located in 56 major cities, there exists a squad or a component of a squad that conducts investigations. The FBI also maintains legal attache offices in 18 foreign countries providing channels through which FBI investigative responsibilities can be met. Several multinational fora are available to professional law enforcement personnel to ensure that cooperation among services continues to expand.