An infrared decoy flare having enhanced infrared intensity is disclosed. The flare includes a case in which an infrared illuminant composition is disposed. The bore diameter and length of the case are advantageously selected to be compatible with preexisting chaff dispensers and their cartridges located on aircraft. The illuminant composition, the nozzle throat area, the geometry of the illuminant composition, and the volume of the combustion chamber are selected such that combustion of the illuminant composition results in an unstable combustion condition during the first second of combustion, thereby increasing the peak intensity of the radiation emitted by the propellant. Preferably, the flare is configured such that the unstable combustion occurs during the first 0.2 to 0.5 seconds of combustion of the illuminant composition.