Raytheon GBU-53/B StormBreaker Lot 12: $708.9M Undefinitized Contract for NATO Multi-Nation FMS Deliveries

Technical Summary

On 6 April 2026, the U.S. Air Force Life Cycle Management Center (AFLCMC) at Eglin Air Force Base awarded Raytheon Company, Tucson, Arizona, a not-to-exceed $708,939,863 undefinitized contract action (UCA) for Small Diameter Bomb Increment II (SDB II) — designated GBU-53/B StormBreaker — Lot 12 production and associated test equipment. The UCA mechanism indicates that final terms and pricing remain subject to definitisation, with the agreed ceiling providing production authority pending negotiation of firm price.

The GBU-53/B StormBreaker is a 93 kg (204 lb), 250 lb-class glide weapon, 176 cm (69 in) in length and 15–18 cm in diameter, fitted with a 48 kg (105 lb) shaped-charge warhead delivering combined blast and fragmentation effects against infantry, armour (including main battle tanks), unhardened structures, and patrol-craft-sized vessels. Wings are produced by the North American division of MBDA. The terminal seeker integrates millimetre-wave (MMW) active radar, uncooled imaging infrared (IIR), and semi-active laser (SAL) modes, supplemented by GPS-coupled inertial navigation and a Link 16 over UHF data link providing in-flight target updates. The published engagement envelope is 60 nmi (111 km) against stationary targets and 40 nmi (74 km) against moving targets. Carriage is qualified on F-15E, F/A-18E/F, and F-35A/B/C platforms.

Of the $338 million obligated at Lot 12 award, $171.5 million — 50.7 per cent — is funded by partner nations through Foreign Military Sales, making the international component at least equal in scale to the United States Air Force and Navy share. Lot 12 contract obligation breakdown, 6 April 2026

The contract includes deliveries under Foreign Military Sales (FMS) to eight partner nations: Belgium, Canada, Finland, Germany, Italy, Norway, the Republic of Korea, and Switzerland. Of the $338 million obligated at award, $171.5 million (50.7 per cent) is funded by partner nations through FMS, indicating that the international component of Lot 12 is at least equal in scale to the United States Air Force and Navy share. The presence of Finland, Germany, and Norway on the FMS list is notable given current NATO munitions recapitalisation priorities and the operational context of ongoing European deterrence requirements. Work is to be completed by March 2030. The AFLCMC, Eglin Air Force Base, Florida, is the contracting activity.

Following Executive Order 14383 of 6 February 2026, future FMS Congressional notifications are now published on the U.S. Department of State website rather than the Defense Security Cooperation Agency (DSCA) portal; this affects the public traceability of any subsequent Finland, Canada, Republic of Korea, and Switzerland case-specific quantities, none of which had been individually notified prior to the Lot 12 award.

Analysis of Effects

The Lot 12 award continues the SDB II production ramp that has sustained a sole-source industrial base at Raytheon’s Tucson, Arizona facility since the first low-rate initial production (LRIP) award. The cumulative production sequence in open sources runs LRIP 1 (12 June 2015, $31 million, 144 all-up rounds), Lot 7 (2021, $212.7 million, 674 USAF and 226 Navy rounds, 900 total), Lot 10 (January 2024, $345 million, more than 1,500 rounds with FMS deliveries to Finland, Germany, Italy, and Norway), and Lot 11 (December 2024, $282.3 million fixed-price-incentive-fee, completion March 2029). Lot 12 at $708.9 million is the largest single award value in the programme to date, although the exact lot size remains undisclosed in the contract notice.

Prior DSCA Congressional notifications anchor four of the eight Lot 12 partner quantities. Norway was approved in June 2023 for 600 all-up rounds at $293 million for its F-35A fleet; Italy was approved in February 2024 for 173 rounds (bundled with an AIM-120C-8 sale); Germany requested 344 rounds within its F-35A acquisition package; and Belgium was approved on 26 July 2024 for 196 rounds at an estimated $115 million for its F-35A fleet. These four DSCA-confirmed cases sum to 1,313 all-up rounds across NATO partners, before Finland, Canada, the Republic of Korea, and Switzerland quantities are added. The Finnish, Canadian, and Swiss requirements are aligned with their respective F-35A acquisition programmes; the Republic of Korea requirement, originally signalled for the F-15K platform, is most plausibly now F-35A-coupled given the Lot 12 multi-nation packaging.

From a munitions safety and logistics perspective, the GBU-53/B is classified Hazard Division (HD) 1.3 for transportation purposes due to its propulsive element and fuzing train, transitioning to HD 1.1 treatment protocols when fully assembled with all-up-round components. Multi-nation FMS deliveries impose alignment requirements across national custody, storage, and handling procedures, all of which must conform to the receiving nation’s national implementation of STANAG 4439 (Policy for the Assessment and Control of Explosives Safety Risks to the Public) and applicable national ammunition management regulations.

The Lot 12 award follows the weapon’s combat debut. In March 2025, F/A-18E/F Super Hornets embarked on USS Harry S. Truman (CVN-75) were photographed carrying GBU-53/B all-up rounds during night strikes against Houthi positions in Yemen, marking the first reported combat employment of the weapon by the United States Navy. The U.S. Navy subsequently declared Initial Operational Capability for SDB II on the F/A-18E/F in February 2026, six weeks before the Lot 12 award. The Lot 12 production timeline therefore reflects a programme transitioning from extended developmental and operational testing into sustained operational employment, rather than a still-maturing capability.

Personnel and Safety Considerations

Ammunition Technical Officers and Weapons Technical Inspectors (WTIs) in FMS recipient nations should anticipate phased In-Service Support (ISS) package activation concurrent with Lot 12 deliveries from 2027 onwards. Carriage configurations vary by platform: the F-15E Strike Eagle accommodates up to 28 all-up rounds via seven BRU-61/A pneumatic Multi-Stores Carriage System racks (four rounds per rack, manufactured by Cobham Mission Systems); the F-35 Lightning II carries 8 rounds internally alongside a pair of AIM-120 AMRAAM missiles, with up to 16 additional rounds on external pylons (24 maximum, configuration-dependent); and the F/A-18E/F employs the L3Harris BRU-55/A smart rack on MIL-STD-1760 stations for paired carriage. The tri-mode seeker assembly contains hazardous materials including IIR focal-plane array components subject to export-controlled handling protocols. Transportation of assembled GBU-53/B rounds under ADR/IMDG classification requires UN0370 (Articles, Explosive, N.O.S.) compliance with net explosive quantity (NEQ) declared per all-up round.

Storage facilities receiving GBU-53/B rounds should confirm their Potential Explosion Site (PES) licensing covers the specific HD 1.3 mass-to-distance requirements. Nations without existing SDB II infrastructure will require Quantity-Distance (QD) surveys prior to accepting delivery, adding to programme timeline considerations that should be reflected in FMS case planning.

Data Gaps

DATA GAP: Exact Lot 12 quantity by nation not publicly disclosed; the $171.5 million FMS-funded share at award provides only a partial constraint. DATA GAP: Definitisation schedule and final contract value not stated. DATA GAP: Finland, Canada, the Republic of Korea, and Switzerland have no public DSCA case-specific notifications; subsequent notifications will be published on the U.S. Department of State arms-sales portal under Executive Order 14383 of 6 February 2026 rather than dsca.mil. DATA GAP: F-35A Initial Operating Capability timelines for Finland, Canada, and Switzerland not independently confirmed against national programme schedules. DATA GAP: NEQ per GBU-53/B all-up round not confirmed in open-source reporting; the 48 kg total warhead mass is published, but the energetic fill mass is not. Figures cited should be independently verified against national Explosive Ordnance (EO) data systems.

AI-assisted technical assessment based on open-source material. Not a formal intelligence product. Sources: U.S. Department of Defense contract announcement, 6 April 2026; AFLCMC/Eglin AFB public contracting notice; Raytheon/RTX public disclosures. Hero image: DVIDS asset 7642430 (VIRIN 230110-O-ZB537-366), photo by Dane Wiedmann, Naval Air Station Patuxent River, 10 January 2023. Public domain — reused under editorial use with non-endorsement disclaimer.