14. Land based strategic bombers carrying nuclear weapons.
Two of the three legs of the American nuclear defense Triad were under the control of the United States Air Force’s Strategic Air Command, which was first activated in 1947 (SAC controlled the ICBMs and the manned bombers). Several US bombers, beginning with the B-29, were designated as aircraft to be used to deliver the atomic, and later the thermonuclear bomb, to targets within the Soviet Union and their allies. Among them were the B-36, B-47, and beginning in 1955, the B-52 Stratofortress, an iconic symbol of American military might both as a nuclear delivery vehicle and as a strategic bomber during the Vietnam War, Operation Desert Storm, The Gulf War, and the War on Terror. The B-52, of which 755 were built, is expected to be continually upgraded and modernized as it has throughout its career, and remain operational within the United States Air Force through the first half of the twenty-first century.
Other bombers and fighter bombers have been designed to carry nuclear bombs as part of their mission, including the FB-111, the B-1, the B-2, and others. The purpose of the manned bomber leg of the triad evolved to become one of removing those launch sites which could not be successfully targeted by the unmanned missiles of the ICBMs and the SLBMs. As those two legs increased in both firepower and accuracy throughout the Cold War and beyond, the manned bombers became less of a first-strike weapon and more of a retaliatory weapon, intended to eliminate targets which survived the first strike and to deploy if necessary against military concentrations and targets of opportunity. All three legs of the nuclear triad remain in place, and all three continue to upgrade and modernize their weapons and their mission in response to changes regarding the perceived threats to the United States and its allies.