Defense Secretary Ash Carter has approved "immediate force-protection steps" in the wake of the tragic shooting incidents in Chattanooga on Thursday.
The gunfire at two different military centers left four Marines dead and a Navy sailor died later.
Secretary Carter has "directed the services to examine additional steps that can be taken to ensure the safety of service members and civilians at military installations and has asked for recommendations by the end of next week."
A spokesman said the Defense Department "continues to gather information on the circumstances surrounding the tragedy in Tennessee, including the specific security measures in place at the two facilities."
He said the secretary's "thoughts and prayers are with the families of the four Marines who lost their lives in this horrific act, and those injured in the shootings.
He is grateful for the service members and first responders whose quick actions likely saved lives."