An energy absorbing strut having, a first end coupled with an inner cylinder, and a second end connected with a hollow rod extending within the inner cylinder. A piston is carried by the rod having an outer surface sealing against an inside diameter of the inner cylinder and forming a compression chamber and a rebound chamber bounded by the piston, the rod having an internal passageway communicating between the compression chamber and the rebound chamber. An inertial mass carried by the rod movable axially on the rod between a closed position against and annular rod passageway and an open position opening the rod passageway and allowing the flow of a hydraulic fluid between the compression chamber and the rebound chamber. A spring acts on the inertial mass biasing the inertial mass toward the closed position. The energy absorbing strut may be used in a blast mitigation system for a military vehicle or other applications for providing shock isolation between two structures.