The U.S. Air Force and Northrop Grumman Corporation completed a full-scale qualification static fire test of the Sentinel intercontinental ballistic missile stage-one solid rocket motor on March 6.

The test performed at Northrop’s facility in Promontory, Utah is a milestone in validating the motor’s design, according to the Air Force.

This test confirms the accuracy of digital engineering models and brings the stage-one solid rocket motor closer to achieving full qualification. This milestone follows static fire tests of the second and third stages, showing progress in the Sentinel program’s development, according to the Air Force.

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 The test results are currently being analyzed by a team of experts from the Air Force Nuclear Weapons Center and Northrop Grumman.

The Sentinel is being developed to replace the existing Minuteman III intercontinental ballistic missile system in use at all three missile bases, including Malmstrom Air Force Base.

The Sentinel program is being restructured following last summer’s Nunn-McCurdy certification process, which was prompted by significant cost overruns.

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In January 2024, the Air Force notified Congress that the Sentinel program exceeded its baseline cost projections, causing a critical breach under the federal Nunn-McCurdy Act, which occurs if the program or average unit procurement cost increases by 25 percent of more over the baseline.

The total program acquisition cost for a “reasonably modified Sentinel program” are now estimated at $140.9 billion, an increase of 81 percent compared to the program’s Milestone B decision in September 2020 when the Air Force awarded a $13.3 billion GBSD engineering and manufacturing development contract to Northrop Grumman.

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The Sentinel program hasn’t been halted, but “the Air Force has suspended work on specific parts of the project while the program office determines the best way forward,” which includes restructuring the program and assessing the acquisition strategy from a technical and contractual standpoint, Capt. Kaylee Schanda, a public affairs officer for the Secretary of the Air Force, told The Electric.

In a Northrop Grumman earning call on Jan. 30, CEO Kathy Warden said “the government has said that they project the restructure to take 18 to 24 months, so we are still very much in that window. And even though they have paused work on some small infrastructure efforts in the command and launch segment, that is reflected in what we have shared with you.”

Schanda told The Electric that the Air Force is using a collaborative approach to make technical trades, look for cost and schedule reductions, and optimize the weapon system design to meet operational requirements.

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Construction of some facilities is underway, but “the Air Force is reassessing the overall project timeline, including military construction at all three missile wings. The Air Force’s budget request for Sentinel will be adjusted to reflect these changes. The revised schedule for transition and deployment activities will not be finalized until the program is restructured,” Schanda told The Electric.

During the Feb. 12 city-county Historic Preservation Advisory Commission meeting, 

Air Force officials take public’s questions on upcoming Sentinel missile project [2024] 

Dr. Wendy Cegielksi, a consultant who’s been working with the Little Shell Chippewa Tribe on a project at St. Peter’s Mission, said that they had concerns about the Sentinel missile project that would run lines and new construction near the mission.

She said the Sentinel project had been halted because of federal budget reviews, which the Air Force said was inaccurate.

Cegielksi referenced a map showing planned construction for Sentinel in the Malmstrom missile field, which the Air Force said was a map of proposed locations that was included in the environmental impact statement for the project that was publicly released in March 2023.

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Cegielksi said the Sentinel project could affect St. Peter’s Mission site and have adverse impact to cultural resources, as well some other Métis or Little Shell tribal resources and historic sites in the area.

Schanda told The Electric that there are currently no land acquisition activities for Sentinel at Malmstrom.

“The Air Force is conducting ongoing environmental surveys as part of a risk reduction effort for potential future construction activities. To date, the Sentinel program has not awarded any construction contracts at Malmstrom. The Air Force is reevaluating the Sentinel construction strategy as part of the program restructure. Final sites for workforce hubs or laydown yards have not been determined. The Air Force is aware that some potential construction may be located near important cultural sites and is dedicated to working closely with the local community to mitigate any potential impacts in the area,” Schanda told The Electric.

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In 2022, the Air Force signed the Sentinel programmatic agreement, that ensures the Air Force is in compliance with the National Historic Preservation Act and has grown relationships with those who place great value on this land.

Air Force signs Sentinel agreement with tribes, preservation, government agencies [2022]

“The Air Force worked with all parties to develop an agreement that balanced the project’s national security priorities with the protection of the cultural resources within the project area. This approach recognized that the lands impacted by the project are the ancestral lands of indigenous peoples represented by over 63 tribal governments,” Maj. Gen. Michael Lutton, 20th Air Force commander, said in a 2022 release. “The agreement is designed to seek tribal input on the identification, documentation, evaluation and protection of sites and objects of tribal significance through all phases and areas of this project. Through a spirit of respect and cooperation, all parties worked to develop the strongest, most effective agreement possible.”

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The agreement provides process and mitigation measures the Air Force will follow with regards to cultural resources and was signed by the Mandan, Hidatsa, and Arikara Nation in North Dakota; seven State Historic Preservation Officers; the Wyoming Attorney General’s office; the National Park Service Interior Region 6, 7 and 8; and the Advisory Council on Historic Preservation.

The Little Shell Tribe of Montana and the Ward County Commissioners also signed the agreement as concurring parties, according to an Air Force release.

On March 6, the Air Force stood up the Site Activation Task Force Detachment 9 at Vandenberg Air Force at Vandenberg Space Force Base in California as part of the ICBM modernization effort.

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Vandenberg’s Western Range is the primary testing ground for the ICBM deterrent architecture and Sentinel “represents a significant update to U.S. nuclear deterrent capabilities,” according to the Air Force.

The Det 9 commander will oversee the daily activities of transitioning from the Minuteman III to Sentinel at Vandenberg, including construction and refurbishment of key facilities essential to the Sentinel program on the installation, and support to the Sentinel test and training missions and personnel.

Similar detachments are scheduled for activation at the missile wings.

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Malmstrom’s is set for April 4 and F.E. Warren Air Force Base in Wyoming is set for April 3. The activation for a detachment at Minot AFB in North Dakota is expected this summer.

F.E. Warren was set the be the first Sentinel installation, following by Malmstrom, then Minot, but that schedule could change as the Air Force restructures the program.