The brittle compressive failure of cubes of columnar saline ice was studied under triaxial (proportional) loading where the ratio of normal stresses (&sgr;11:&sgr;22:&sgr;33) was varied in a systematic manner using a true multiaxial loading system. The strain rate in the direction of the greatest applied compressive stress was 6¿10-3 s-1 and the temperature was -10 ¿C. The failure surface is faceted and reveals three regimes: (1) of lower across-column confinement where the along-column confinement has no significant effect on the major across-column stress at failure, but where the minor across-column stress raises the strength; (2) of higher across-column confinement where along-column confinement now raises the major across-column stress at failure; and (3) of predominantly along-column loading where the along-column failure stress increases in proportion to the smaller of the two across-column confining stresses. Each regime shows a high sensitivity of strength to the appropriate confining stress. The behavior is explained in terms of the frictional crack sliding-wing crack mechanism of brittle compressive failure.¿ 1997 American Geophysical Union