PPD's role is to provide law enforcement and protective security services for The Pentagon and other Office of the Secretary of Defense (OSD) activities in the National Capital Region.

Prior to 1971, the General Service Administration's (GSA) United States Special Policeman (USSP) conducted law enforcement, safety and security functions at the Pentagon.

However, in response to a growing number of disruptive incidents throughout the country affecting federal facilities under GSA control, attention to the security program had to be re-examined.

[citation needed] On March 4, 2010, a gunman, identified as John Patrick Bedell, who espoused anti-government views, shot and wounded two officers at a security checkpoint in the Pentagon Metro station.

The K-9 Unit is organized into several teams (canine and handler) that provide both proactive and reactive law enforcement functions in order to ensure a safe working environment at the Pentagon Reservation and its other associated properties.

The Officers of the PPD Special Operations K-9 Unit are dedicated to duty and ready to respond to any situation at a moment's notice.

In achieving their goals, PSU personnel must be highly trained and experts in numerous law enforcement skills in order to provide a premier security posture for, and according to specification of the individual principal's needs.

The PSU serves as the single point of contact for PPD on all ceremonies in honor of visiting dignitaries hosted by the Office of Secretary of Defense and the Chairman of the Joint Chiefs of Staff.

For PSU personnel, strong diplomatic skills and the ability to effectively operate in high-pressure situations are extremely important.