AGM-28 Hound Dog
U.S. Air Force AGM-28 Hound Dog air-to-surface missiles were carried under the wings of B-52 bombers. With a range of several hundred miles, it was intended to help the bombers penetrate by suppression of enemy air defense in the path to the principal target. They served from 1960 to 1975, and were retired for poor reliability and their degradation of B-52 flight performance, especially as B-52 missions went to low altitude where aerodynamic drag was even more of a concern.
There are somewhat conflicting reports on the size of its nuclear warhead. The Federation of American Scientists describes it generically as 4 Mt,but other reports specifically identify it as a W28 known to have a yield between 70 kt and 1.45 Mt. It had Category A, and then B, Permissive Action Links.