Earlier this week I attended a very thoughtful and stimulating debate on the modernization of U.S. nuclear missiles hosted by the Project on Nuclear Issues (PONI) at CSIS. The debate addressed the merits and downsides of two planned U.S. nuclear delivery system recapitalization efforts: the Ground Based Strategic Deterrent intended to replace the Minuteman III ballistic missile system, and the Long-Range Stand-Off (LRSO) cruise missile that is supposed to replace the AGM-86 air-launched cruise missile (ALCM). The ALCM is a dual-capable missile, meaning it can carry either a nuclear or conventional payload. While the LRSO is planned to be only used for nuclear missions, in a conflict scenario it would be hard to discern between it and a conventionally-armed cruise missile until the moment of impact.
One topic raised during the debate was the effect of the LRSO on strategic stability, an important and hotly debated issue. The advocates of the LRSO downplayed the destabilizing potential of the system by pointing out that the United States has used dual-capable cruise missiles in past conflicts. Concerns about strategic stability should be kept in mind, they argued, but the United States has a track record of using dual-capable cruise missiles while safely navigating such concerns.
This argument may be technically true, but it ignores a critical fact: all past uses of dual-capable cruise missiles were in conflicts with countries that did not have nuclear weapons—not between two nuclear-armed countries. Policymakers should be wary of arguments that use historical evidence to dismiss or downplay the negative effects of LRSO on strategic stability because there are no adequate past cases to test such arguments against.