When Jimmy Carter cancelled the B-1A on 30 June 1977, he did so believing that air-launched cruise missiles carried by B-52s, together with the still-secret stealth bomber programme that would become the B-2, made a costly new penetrating bomber unnecessary. The decision was hugely controversial and became a political flashpoint.

Ronald Reagan campaigned partly on restoring it, and in 1981 his administration approved 100 B-1B aircraft. The revived jet was not the old B-1A: it traded the A-model’s Mach-2-plus high-altitude dash for a stronger structure, higher weights, fixed engine inlets and radar-absorbent shaping that cut its radar cross-section to roughly a hundredth of the B-52’s. It was, in effect, a different aircraft built for a different way of getting to the target — fast and low, rather than high and fast.

A bomber built to penetrate at low level faces a contradiction. To take off heavy, loiter efficiently and land safely it wants a long, straight wing; to punch through the dense low-altitude air at high speed without being torn apart by turbulence it wants a short, sharply swept one. The variable-sweep wing solves both: spread to 15° for takeoff and cruise, and swept back to 67.5° for the high-speed dash. The penalty is weight and mechanical complexity in the wing pivot, but for the B-1B’s fast-and-low mission it was judged worth it — the same reasoning that gave swing wings to the F-111, F-14 and Soviet Tu-160.

The B-1B entered service as a nuclear penetrator, but it never carried nuclear weapons in combat. After the Cold War the type was progressively removed from the nuclear mission — its nuclear wiring and hardware stripped out through the 1990s and formally accounted for under later arms-control treaties — and rebuilt as a purely conventional bomber. Upgrades gave it precision JDAMs, a targeting pod, a moving-target radar and a data link, turning a jet designed to deliver free-fall nuclear bombs into the most prolific precision-strike platform of the post-9/11 wars. It is one of the clearest examples of a strategic aircraft finding an entirely new career.

The B-1 is a big, complex, ageing four-engine aircraft, and it costs accordingly. Program flyaway costs in the late 1990s were commonly cited around US$280–320 million per aircraft, and the cost per flight hour is frequently quoted in the US$60,000–70,000 range — among the higher figures in the bomber fleet. Low-altitude, high-speed flying is hard on airframes, and years of heavy use over Afghanistan and Iraq wore the fleet down. Rising maintenance costs and airframe fatigue are among the reasons the US Air Force is retiring the type as the B-21 Raider comes online. Treat any single dollar figure as an order-of-magnitude estimate rather than an audited number.