Abstract: A heat sensitive case/nozzle interface is provided for an insensitive propellant-loaded munition such that the interface loses its structural integrity when high external heat is applied. The joint between a rocket case housing a rocket motor and nozzle forming the interface is received by an internal spring retainer positioned in a first groove in the case or nozzle in cooperation with a fusible material housed in an aligned second groove in the nozzle or case, respectively. A plurality of aligned openings extend into said first and second grooves. When the rocket is exposed to a high ambient temperature greater than melt temperature of the fusible material but lower than the auto-ignition temperature of the rocket, the fusible material melts and is forced through said holes by the spring retainer permitting the nozzle to separate from the case rendering the rocket motor safe if it auto-ignites.