Nuclear warheads are processed at Sandia National Laboratory, Kirtland Air Force Base, Albuquerque, NM, for transhipment to and from US nuclear combat forces. The largest US nuclear weapons storage area, named the Kirtland Underground Munitions Storage Complex (KUMSC), is located nearby.
Speculation is that the warheads and capsules are encased in pressurized containers which if depressurized will cause destruction of crucial elements of the units. Pressurization may be by way of a special gas. This map shows an aircraft facility at Kirtland which appears to be where warheads and capsules may be pressurized for shipment by air.