LRSO

The Long-Range Standoff Weapon (LRSO) is a U.S. nuclear-capable air-launched cruise missile being developed by the Air Force to replace the aging AGM-86B Air-Launched Cruise Missile (ALCM), which entered service in the early 1980s. Designated AGM-181A, the LRSO is designed to be carried by the B-52H Stratofortress and, eventually, the B-21 Raider, giving bomber crews the ability to strike heavily defended targets from outside the range of advanced integrated air defenses.

The program is a central element of the broader U.S. nuclear modernization effort, which also includes the B-21 bomber, the Sentinel ICBM, and the Columbia-class ballistic missile submarine. Raytheon (now RTX) was selected in 2021 as the sole contractor after a competitive development phase that had also included Lockheed Martin. The missile will carry the refurbished W80-4 warhead, a life-extended variant of the W80 produced by the National Nuclear Security Administration.

LRSO has drawn sustained debate among arms control analysts. Critics, including former Secretary of Defense William Perry, have argued that nuclear cruise missiles are destabilizing because adversaries cannot easily distinguish nuclear from conventional cruise missiles in flight, raising escalation risks. Proponents in the Pentagon counter that a credible standoff capability is essential to penetrate modern Russian and Chinese air defenses such as the S-400 and HQ-9, and that retiring the ALCM without replacement would erode the air leg of the nuclear triad.

For Model UN and policy researchers, LRSO is frequently cited in committees dealing with strategic stability, NPT Article VI disarmament obligations, and U.S.–Russia arms control after the lapse of the INF Treaty in 2019 and the scheduled expiration of New START in February 2026. It is also relevant to debates on the modernization of all five recognized nuclear-weapon states under the NPT.