The dynamic strength of an optical glass of the K8 type was studied under submicrosecond impact loading conditions. A 80-ns-long pressure impact was generated by a laser radiation pulse acting upon an aluminum foil. The free sample surface velocity was measured by a laser differential interferometer. The onset of fracture at the free surface was detected using a He-Ne laser radiation reflected from a crack appearing as a result of the glass cleavage. The experimental data on the dynamic strength of a glass under submicrosecond impact loading conditions are obtained for the first time. For the K8 glass studied, the critical cleavage stress amounts to 0.45 ± 0.03 GPa. Experimental investigations of the time characteristics of the fracture process, as well as the results of a fractographic analysis of the cleavage zone, do not unambiguously confirm the existence of the stage of damage accumulation during the fracture of inorganic glasses.