VANDENBERG SPACE FORCE BASE, California, September 21 — The US Air Force and Northrop Grumman have stacked a fully integrated but inert LGM-35A Sentinel intercontinental ballistic missile on a test pad here, the first time the weapon has been assembled vertically as a complete article rather than as a set of components on a drawing board. The milestone, announced by Northrop Grumman on 14 September, came at the end of a four-month dry-run the company calls Pathfinder.
All missile stages, propulsion elements, the shroud and associated components were brought together after travelling cross-country by specialised transport and mobile crane operations, then stacked and de-stacked on the pad. No live propellant, no warhead.
Under the hood, this is a structural and integration rehearsal — the missile equivalent of a dress fitting, and about as explosive.
What Pathfinder actually proved
Northrop Grumman said the vertical assembly “demonstrates the design and integration of the missile and is a major step toward the Sentinel missile’s design and suitability evaluation for flight test in 2027.” The company and the USAF 719th Test Squadron also completed the first flight test Critical Design Review for Sentinel, validating that the missile meets all Air Force requirements for performance, safety and schedule ahead of that first flight test.
The review is a formal milestone in the acquisition process; clearing it means the design is considered sound enough to move forward. Getting a missile of this size across the country and upright on a pad is its own engineering problem.
The components moved by specialised transport and mobile crane operations — the sort of logistics that rarely make headlines but tend to decide schedules.
The wider programme
Sentinel is the Air Force’s effort to replace the Minuteman III, the land-based leg of the US nuclear triad. The programme has drawn scrutiny over cost, and the vertical assembly and design review are the kind of concrete progress that answers some of it. Earlier work includes acoustic testing for the LGM-35A conducted in partnership with Lawrence Livermore National Laboratory in December 2025, and Northrop Grumman breaking ground on an expanded facility in Utah.
The detail that matters now is the calendar. The first flight test is scheduled for 2027, and everything since the Pathfinder dry-run has been pointed at it.
