The active service life of the B-58 was destined to be rather short. Phaseout of the B-58 fleet was ordered by Secretary of Defense Robert McNamara in December 1965, since it was felt that the high-altitude performance of the B-58 could no longer guarantee success against increasingly sophisticated Soviet air defenses. Although SAC had never been happy with the relatively limited range of the B-58 and felt that the Air Force, through congressional pressure, had forced the B-58 on them, the aircraft had gone through a long gestation period during which many bugs had been wrung out of the system, and it was now thought to be a valuable and effective weapons system. Consequently, SAC pressed the Defense Department for the retention of the B-58, at least until 1974. However, the decision of 1965 was to stand.