60,000 Untested Combinations: The Framework That Replaced NATO's Cancelled Ammunition Standards

The Standard That Was Deliberately Cancelled

STANAG 4385 governed the dimensional interchangeability of 120mm × 570 smoothbore tank ammunition across NATO. It guaranteed a fixed geometric envelope: any round from any manufacturer that fell within the specified dimensions would physically seat and fire in any compliant gun tube. The standard served the Alliance for decades, and its withdrawal in April 2016 was not administrative neglect. It was a deliberate technical decision driven by a reality that dimensional standardisation could no longer safely address.

Modern 120mm armour-piercing fin-stabilised discarding sabot (APFSDS) rounds operate at significantly higher chamber pressures than the propellant systems for which STANAG 4385 was designed. The safe maximum load for a given round depends not on whether it fits the chamber but on the specific barrel design, metallurgy, and accumulated wear of the gun tube it is loaded into. A round cleared for a new-production Leopard 2A7 barrel may produce unsafe pressures in an older 2A4 tube of the same nominal calibre. No dimensional standard can capture this variable across thirty-plus NATO nations with gun tubes spanning multiple generations, manufacturers, and maintenance histories.

The decision to withdraw rather than revise STANAG 4385 reflected a broader recognition within the NATO Army Armaments Group (NAAG, AC/225) that the form-and-fit approach to ammunition interchangeability had reached its technical limit for high-pressure systems. Dimensional compliance and safe function had become two different questions, and answering the first no longer reliably answered the second.

The Three-Pillar Certified Interoperability Framework

The replacement for STANAG 4385 is not another STANAG. It is a three-pillar certified interoperability framework that trades the simplicity of a dimensional envelope for the accuracy of performance-verified certification. Each pillar addresses a distinct aspect of the interoperability problem, and all three must be satisfied before a given round can be operationally employed in a given weapon system.

The framework is deliberately decentralised. No single document or authority controls interoperability certification. AC/326 certifies the round is safe in general terms. NAAG LCGLE confirms it is safe in a specific weapon system through platform-originating nation firing trials. The operational clearance result — which rounds are authorised for which platforms — is held by the nation that originates the weapon system. Non-originating nations operating the same platform must obtain clearance data through NARP mutual certificate recognition or bilateral exchange; there is no centralised Alliance-wide clearance database. NSPA’s Ammunition Support Partnership supports multinational procurement coordination but does not retain this interoperability data for all nations. This layered, nationally-held approach accommodates the diversity of barrel conditions, ammunition variants, and national fleet configurations across the Alliance — but it also means that interoperability verification depends on nations being willing to share certification data bilaterally.

Studies under NAAG LCGLE are ongoing to assess whether any updated form-and-fit standard for the 120mm family is now feasible without re-imposing the innovation barriers that drove the 2016 withdrawal. As of March 2026, no new STANAG has been ratified.

Ukraine: The Operational Stress Test

The Ukraine conflict provided the first large-scale operational test of NATO ammunition interoperability since the Cold War — and the results confirmed every structural weakness that the standardisation community had documented for decades.

Ukrainian forces simultaneously operated seventeen different types of 155mm howitzer, supplied by multiple Western donor nations over a compressed timeline. Against these seventeen platform types, nearly fifty different models of 155mm high-explosive shell circulated through Ukrainian logistics chains. The ammunition came from different nations, different manufacturers, and different production eras. Some combinations were tested and documented in NATO interoperability data. Most were not.

NATO-wide research subsequently identified more than 60,000 theoretical untested firing-and-ammunition combinations across the Alliance’s land-domain inventory. The scale of this number is worth pausing over. Comprehensive testing of 60,000 combinations is physically and financially impossible. Each firing trial consumes ammunition, gun tube life, range time, and instrumentation resources. Even at an aggressive testing tempo, clearing the full matrix would take decades.

Ballistic Incompatibility in Practice

The operational consequence in Ukraine was not abstract. Components reported in AOP-29 as interchangeable were sometimes ballistically incompatible in practice. The core problem is straightforward: different combinations of propelling charge and projectile produce different muzzle velocities. Fire control software must be calibrated for the specific muzzle velocity of the ammunition being fired to calculate accurate ballistic solutions. When ammunition is mixed across manufacturers and production lots — as it inevitably was in Ukrainian logistics chains — muzzle velocity variations must be reconciled in the fire control system.

For a single gun crew firing a single type of ammunition, this is a solved problem. For a brigade-level logistics system drawing ammunition from multiple donor nations, mixing charge types and projectile variants across battery positions, and operating fire control software configured for a different national ammunition baseline, accurate delivery becomes a fire control integration challenge that no existing STANAG fully addresses.

The four standardisation dimensions identified in the source analysis — form and fit, functioning and safety, delivery and accuracy, handling and logistics — were all exposed simultaneously. Rounds that physically seated correctly (form and fit) sometimes produced unacceptable chamber pressures in older barrel variants (functioning and safety). Rounds that were individually safe produced inconsistent ballistic performance when mixed with other nominally interchangeable types (delivery and accuracy). And the sheer variety of ammunition types overwhelmed logistics tracking systems designed for national inventories, not multinational supply chains (handling and logistics).

The 155mm Problem: STANAG 4425 and the AOP-29 Time Capsule

STANAG 4425 remains active. Unlike STANAG 4385, it has not been withdrawn. But its status requires careful interpretation. STANAG 4425 is a procedural standard — it governs how nations report and assess whether their ammunition is interchangeable with allied systems. It is not a binding certification or a technical interoperability guarantee. It is a reporting framework.

The interchangeability data that STANAG 4425 compiles is published as AOP-29, maintained by the Surface-to-Surface Artillery Panel of AC/225 Land Capability Group 3, Sub-Group 2. AOP-29 covers 155mm (Part 1), 105mm (Part 3), and 81mm/120mm mortars. Its critical limitation is currency: AOP-29 contains no data for any system fielded after the mid-1990s.

Thirty years of new howitzers have entered NATO service since the last substantive AOP-29 update. Extended-range projectiles, base-bleed and rocket-assisted variants, new propelling charge designs, and insensitive munitions reformulations are all absent. The twelve nations that joined NATO after the Cold War — from the Czech Republic and Poland in 1999 through Finland and Sweden in 2023–2024 — brought artillery systems and ammunition inventories that appear nowhere in the compilation. AOP-29 is not merely incomplete. For practical purposes, it is a historical document being treated as a current reference.

The Digital Living AOP-29

NAAG’s Integrated Capability Group Indirect Fire (ICGIF), Sub-Group 2 on Ballistics, Effectiveness and Fire Control Software, is leading the development of a digital, living replacement for the static AOP-29 compilation. The digital format is intended to allow continuous updates rather than periodic static editions. The scope includes post-1995 howitzer and ammunition systems, data from post-Cold War NATO accession nations, firing data gathered from Ukraine operational experience, and results from the ICGIF SG/2 rapid testing programme initiated in response to the conflict.

The release target was end-2025. Whether that target was met has not been confirmed in open sources as of March 2026. The ambition is correct: a continuously updated digital interoperability database accessible to allied nations would transform the operational utility of STANAG 4425 from a procedural shell into a genuine interoperability tool. The question is whether the institutional and national-security barriers to data sharing — particularly industry proprietary ballistic data and national test firing results — can be overcome at the speed the operational environment demands.

The Joint Ballistics Memorandum of Understanding

For the five principal 155mm nations — the United States, France, Germany, Italy, and the United Kingdom — the binding technical interoperability instrument is not STANAG 4425 or AOP-29. It is the 2009 Joint Ballistics Memorandum of Understanding (JBMoU), registered as TIAS 09-1218 under the US Treaties and Other International Acts Series and entered into force on 18 December 2009. Its stated purpose is to “maximize the potential for the achievement of Interchangeability of the Participants’ 155MM Weapon and Ammunition Systems.” Where full interchangeability is not achievable, the JBMoU requires that ammunition systems be interoperable “at a minimum from breech to target.”

Historical Lineage

The JBMoU did not emerge from nothing. Its predecessor was the Quadrilateral Ballistics Memorandum of Understanding between the United States, United Kingdom, Italy, and West Germany. NATO Basic Military Requirement 39 was agreed in 1963, establishing the requirement for a close-support 155mm artillery capability that led to the FH70 programme and the standardisation of the 39-calibre barrel with an approximately 18-litre chamber volume. The projectiles developed under this framework conformed to the Quadrilateral Ballistics Agreement, ensuring that ammunition manufactured by any of the four signatory nations could be fired from weapons produced by the others. The subsequent move to 52-calibre barrel length and 23-litre chamber volume — now the baseline for every modern NATO-standard 155mm weapon system — expanded the performance envelope while retaining the interchangeability principles established by the original agreement. The 2009 JBMoU formalised and expanded this framework into a binding five-nation instrument (adding France to the original four) covering ballistics coefficients, propelling charge performance characterisation, gun-barrel compatibility assessment, and the interchangeability envelope for modular charge systems.

What the JBMoU Actually Governs

The JBMoU operates at a technical depth that AOP-29 does not approach. It standardises the ballistic characteristics of 155mm ammunition so that a round manufactured by one signatory nation can be fired from any JBMoU-compliant weapon system and achieve predictable ballistic performance. This extends beyond dimensional compatibility to encompass propelling charge energy output, projectile drag coefficients, muzzle velocity bands, and the firing data required by NATO Armaments Ballistic Kernel (NABK) fire control software — standardised under STANAG 4537 — to compute accurate trajectories. Rheinmetall’s L52 cannon system, now in production and in service with nine NATO allies and partners, is explicitly designed to NATO JBMoU standard. This compatibility is the primary selling point for artillery modernisation programmes, including the proposed M109A7 Paladin upgrade for the US Army.

The Gap Between Compliance and Interoperability

Ukraine has provided the first large-scale operational test of JBMoU-era ammunition in multinational conditions — and the results expose the distance between standards compliance and true interoperability. As Major Eric Johnson of the US Army’s 56th Theater Multi-Domain Command documented in the Modern War Institute (November 2025), drawing on his experience as an operational fires advisor with Security Assistance Group–Ukraine: although JBMoU and STANAG-compliant 155mm rounds are physically compatible and safe to fire in approved combinations, they are not technically interoperable until a battery can achieve accurate first-round effects with ammunition from another nation. That requires what Johnson terms “accurate weapon and ammunition data” — shell weight, fuze weight, propellant efficiency, barrel wear, and historic muzzle velocity for each specific gun-ammunition combination. No centralised source for this cross-national firing data exists.

Johnson documented a specific example of compliance failing to deliver interoperability: Ukrainian forces found that US-supplied inductive fuze setters, fully compliant with STANAG 4369 and AOP-22, could not programme fuzes from a non-US NATO nation because the fuze setter software simply did not have that fuze type in its database. Both items were individually STANAG-compliant. Neither was interoperable with the other without a manufacturer software update. Ukrainian forces developed the Kropyva fire control system as a workaround — generating expedient firing tables from two or three test shots at maximum range to predict ballistic performance for unfamiliar ammunition combinations.

JBMoU-compliant ammunition — including the Rheinmetall V-LAP family validated to ranges beyond 70 km from L52 systems using Extended Range Charge (ERC) propellant technology, and KNDS and Junghans Defence rounds under the 2024 NSPA-coordinated €1.1 billion multinational contract — remains the procurement baseline for the five signatory nations. In 2019, Rheinmetall Denel Munition achieved a world record of 76 km at the Alkantpan Test Range in South Africa from a non-JBMoU-conforming 52-calibre gun, demonstrating the potential performance envelope that JBMoU-standard systems are approaching.

The JBMoU functions as a bilateral-to-multilateral technical depth layer sitting beneath the broader STANAG 4425 procedural framework. Nations outside the JBMoU — the majority of the Alliance — rely on AOP-29 and national testing, with all the currency limitations that implies. The Finabel European Army Interoperability Centre noted in its 2024 focus paper on NATO ammunition production that the JBMoU was adopted specifically so that 155mm ammunition produced in one signatory country could be fired by the artillery weapons systems of another — but that European production structures, managed across nine principal manufacturers, limit the ability of European states to surge production to the degree the US can through its government-owned arsenals.

The Cannon Calibre Gap Nobody Is Talking About

The interoperability problems documented for 120mm and 155mm are well understood within the standardisation community, even if they remain poorly communicated to the wider defence audience. A less visible but potentially more consequential gap exists at the cannon calibre level.

There are minimal interchangeability standards for 30mm × 173 — the most widely fielded NATO cannon calibre, used across a range of infantry fighting vehicles, self-propelled anti-aircraft systems, and naval close-in weapon systems. The standard that does exist, AEP-97, is limited in scope and does not provide the comprehensive interchangeability matrix that AOP-29 attempts for artillery calibres.

For 40mm case-telescoped (CT) ammunition — the ammunition type entering service with the Anglo-French 40CTAS weapon system on Ajax and EBRC Jaguar — there are no interchangeability standards at all. This is a fundamentally different technology: the projectile sits inside the cartridge case surrounded by propellant, producing rounds roughly half the length of conventional 40mm ammunition. A rotating breech mechanism feeds from the side and rotates 90 degrees to align with the barrel — a chamber geometry and operating cycle incompatible with any other NATO cannon system. The 40CTAS is not covered by any STANAG or NATO interoperability agreement. CT40 ammunition cannot be fired from conventional 40mm weapons, and conventional 40mm ammunition cannot be fired from the 40CTAS.

The supplier base reflects this isolation. CTA International — an equal-shares joint venture between KNDS (formerly Nexter) and BAE Systems, based in Bourges, France — is the sole manufacturer of both the weapon and its ammunition. After more than three decades of development, the customer base remains confined to two nations: the United Kingdom (Ajax) and France (EBRC Jaguar and the Thales/KNDS RapidFire naval close-in weapon system, now deploying on Jacques Chevallier-class logistics support ships). In June 2025, the French DGA awarded KNDS a contract for 25,000 rounds with full-rate production from 2026 — the first significant production order. The ammunition suite includes APFSDS-T armour-piercing rounds (penetrating over 140mm RHA at 1,500m), GPR programmable airburst rounds (effective to 2,500m with 125m² ground coverage), and KE-AB kinetic energy airburst rounds optimised for counter-UAS and aerial threats.

The United States evaluated the 40CTAS for its Stryker and Bradley platforms in 2018, with BAE Systems demonstrating the weapon at Fort Benning. The US Army chose not to proceed, opting instead for the 50mm XM913 Bushmaster chain gun for its XM30 Mechanized Infantry Combat Vehicle (the Bradley replacement). Reports indicate that recoil characteristics — approximately 20,000 lb of recoil force — contributed to integration difficulties on Ajax and factored into the US decision.

50mm: The US Goes Alone

Rather than adopt the Anglo-French 40mm CT, the United States chose a different path entirely. The XM913 50mm Bushmaster chain gun — a 300 kg externally powered weapon designed by Northrop Grumman at Picatinny Arsenal — fires a proprietary 50×228mm cartridge at a cyclic rate of approximately 200 rounds per minute. The weapon is an evolution of the Mk44 Bushmaster chain gun family already fielded across NATO, but upscaled to a calibre that no other allied nation uses or has plans to adopt.

The ammunition suite, developed by General Dynamics Ordnance and Tactical Systems (GD-OTS) at their Scranton, Pennsylvania facility, comprises three natures. The XM1204 High-Explosive Air-Bursting Tracer (HEAB-T) features three selectable detonation modes — point detonation, delay, and programmable airburst — providing flexibility against infantry, light armour, and aerial targets including UAS. The XM1203 Armour-Piercing Fin-Stabilised Discarding Sabot Tracer (APFSDS-T) is optimised for defeating armoured fighting vehicles. The XM1202 Target Practice Tracer (TP-T) provides a ballistically matched training round. All three use the same 50×228mm cartridge case — a calibre manufactured exclusively by GD-OTS with no second source, no multinational production agreement, and no NATO Maintenance and Supply Agency (NAMSA) stock number.

The XM913 is the primary armament of the XM30 Mechanized Infantry Combat Vehicle (MICV), the US Army’s programme to replace the M2 Bradley. Two competing prototypes — the American Rheinmetall Vehicles (ARV) Lynx and the General Dynamics Land Systems (GDLS) Griffin III — were delivered with the XM913 as government-furnished equipment. Sixteen cannons were produced for the competitive prototype phase, with initial prototype vehicles delivered from July 2026.

However, the programme hit a significant obstacle in February 2026 when US Army Chief of Staff General Randy George and Army Secretary Dan Driscoll declined to sign the Milestone B decision — the approval that would have authorised low-rate initial production. The programme is now under review, with the Army citing affordability concerns and the need to reassess requirements against evolving threats. This pause introduces uncertainty not only for the XM30 platform but for the entire 50mm ammunition industrial base, which has no other customer.

No NATO ally shares the 50×228mm calibre. European nations operating Lynx-family vehicles — notably Hungary, which took delivery of 218 Lynx KF41 IFVs from 2023 — selected the 30mm Mk30-2/ABM lance turret, not the 50mm configuration. Germany’s own next-generation IFV discussions centre on 30mm×173 or 35mm, not 50mm. If the XM30 proceeds to production, US mechanised infantry will operate a cannon calibre that cannot be supplied by any allied nation and whose ammunition has no interoperability pathway with any NATO standard. The 50mm represents the most extreme case of calibre isolation in the Alliance — a deliberate national choice to optimise for lethality at the cost of multinational ammunition commonality.

The result is a calibre fragmentation across the Alliance that has no precedent at this scale. NATO IFVs and cannon-armed platforms currently field or are procuring weapons in 20mm, 25mm, 30mm, 35mm, 40mm CT, and 50mm — six distinct calibres with no cross-compatibility and no Alliance-level standardisation agreement governing any of them beyond the limited scope of AEP-97 for 30mm×173. As European Security & Defence noted in its analysis of European IFV armament choices, this stands in sharp contrast to the standardisation achieved at 120mm and 155mm, where at least procedural frameworks exist even if technical interoperability remains incomplete.

NAAG LCGLE has a study underway to assess standardisation needs for these calibres before the interoperability problem that has plagued 120mm and 155mm repeats at the cannon level. The study is timely but may already be too late to influence the procurement decisions now being made. NATO nations are selecting infantry fighting vehicles and cannon-armed platforms for the next thirty years against an ammunition interoperability baseline of effectively zero for the newest calibres. The procurement decisions being made today will determine whether the Alliance faces a cannon-calibre interoperability crisis in the 2030s comparable to the one it faces now at 120mm and 155mm.

Industrial Positioning vs Standardisation

The absence of ratified STANAGs has not created a vacuum in the procurement landscape. It has created a space in which industrial framework contracts and bilateral agreements function as de facto interoperability references.

Rheinmetall: The 120mm Framework

In July 2025, Rheinmetall signed a framework agreement with NSPA covering multiple types of 120mm tank ammunition for allied nations. An initial order of approximately €200 million was placed in February 2026. The technical specifications of this contract — negotiated through NSPA and structured around the three-pillar certified interoperability framework — function as the de facto operational interoperability reference for 120mm ammunition in the absence of a ratified STANAG. Nations procuring 120mm tank ammunition through NSPA are, in effect, adopting Rheinmetall’s qualified product baseline as their interoperability standard.

KNDS: The SHARD APFSDS

France’s KNDS division is positioning its SHARD 120mm APFSDS round — ordered by France in early 2026 with a target of replacing current Leclerc ammunition by 2030 — as ITAR-free and cross-platform compatible with Leopard 2, Leclerc, and Abrams. This is industrial positioning ahead of any standardisation process. KNDS is establishing interoperability credentials through commercial certification and bilateral clearance rather than waiting for a multilateral STANAG that may never come.

The €1.1 Billion 155mm Multinational Contract

NSPA’s 2024 €1.1 billion multinational contract for 155mm ammunition — awarded to KNDS and Junghans Defence — represents the largest single NATO ammunition procurement in recent history. It was structured around JBMoU compliance for the signatory nations and STANAG 4425 procedural reporting for the broader coalition. The contract illustrates the dual-track reality of NATO ammunition procurement: a technical depth layer for the nations with bilateral agreements, and a procedural framework for everyone else.

Without multilateral standards, procurement contracts and bilateral agreements are filling the interoperability gap. This is pragmatically effective but structurally fragile. Framework contracts expire. Bilateral agreements cover signatories, not the Alliance. And industrial interoperability claims — however well-founded — are not the same as independently verified, multilaterally ratified standards.

Seven Structural Barriers That Will Not Resolve Themselves

The source analysis identifies seven persistent barriers to NATO ammunition interoperability. Each has been documented repeatedly in Alliance working groups. None has been resolved.

1. Standardisation timelines exceed operational reality. The NATO standardisation process, requiring consensus across 32 nations with varying technical capabilities and industrial interests, operates on multi-year cycles. Wartime ammunition interoperability problems emerge in weeks. The process that produces STANAGs cannot respond at the speed at which interoperability gaps are exposed in conflict.
2. Testing is expensive and national certifications are not mutually recognised. Live-fire testing of ammunition-platform combinations consumes significant resources. Each nation conducts its own certification programmes, and the results are not automatically recognised by other nations. A round cleared by Germany for Leopard 2A7 may require separate testing by Greece before it can be used in Greek Leopard 2A6 fleet, even though the ballistic question is substantially the same.
3. Thirty-two-nation consensus requirements slow reform. Any revision to a STANAG requires consensus. For technically complex standards involving national industrial interests, proprietary data, and sovereign certification authority, achieving consensus among 32 nations is structurally difficult. The pace of standardisation reform is set by the slowest participant.
4. Industry proprietary data blocks information exchange. Ammunition interoperability certification requires detailed ballistic data: internal ballistics, chamber pressure curves, muzzle velocity distributions, projectile stability parameters. This data is commercially sensitive. Manufacturers are reluctant to share it through multilateral channels, and nations often lack the legal authority to compel disclosure. The information needed for interoperability certification is frequently the information that industry is least willing to provide.
5. National legislation creates conflicting requirements. Ammunition safety regulation varies across NATO nations. Certification criteria, proof testing requirements, acceptance standards, and liability frameworks differ. A round that meets German proof law requirements may not satisfy French DGA certification criteria, not because it is unsafe but because the regulatory frameworks define safety differently.
6. Batch qualification cannot scale to wartime consumption. In peacetime, ammunition is procured in planned batches with full quality assurance and acceptance testing. Wartime consumption rates — as demonstrated in Ukraine — exceed peacetime production capacity by orders of magnitude. Batch qualification processes that take weeks or months cannot be applied at the tempo required to sustain high-intensity operations.
7. STANAG compliance does not guarantee ballistic compatibility. Even rounds that are nominally STANAG-compliant can produce different ballistic performance when paired with different charge-and-projectile combinations. Fire control software must be calibrated for the specific muzzle velocity profile of the ammunition being fired. Mixing STANAG-compliant rounds from different sources without fire control adaptation produces inaccurate fires — a problem that physical interchangeability standards were never designed to address.

What WOME Practitioners Need to Know Now

The migration from prescriptive dimensional STANAGs to the three-pillar certified interoperability framework has direct operational implications for WOME professionals deploying to multinational theatres. The rules that governed ammunition interchangeability during initial training may no longer apply, and the authoritative references have changed.

120mm: National Certification Is the Reference, Not a STANAG

There is no active STANAG for 120mm smoothbore tank ammunition. WOME practitioners must confirm platform clearance status for each round-and-barrel combination through the certification data held by the nation that originates the weapon system platform. That clearance is produced by AC/326 safety certification and NAAG LCGLE weapon clearance trials, but the operational data — which specific rounds are authorised for which specific barrel variants — is retained nationally, not in a centralised Alliance repository. Where a non-originating nation operates the same platform, clearance data must be obtained through NARP mutual certificate recognition or direct bilateral exchange with the originating nation. NSPA’s Ammunition Support Partnership can support procurement coordination but does not hold this data for all nations. If a specific ammunition nature has not been cleared through this framework for the platform variant in theatre, it is not authorised for use regardless of dimensional compatibility.

155mm: AOP-29 Cannot Be Assumed Current

Any system fielded after approximately 1995 will not appear in AOP-29. This includes most of the howitzers currently in NATO service and all extended-range and precision-guided ammunition types. Verification through ICGIF SG/2 channels or direct national certification exchange is required before treating ammunition components as interchangeable. The assumption that “STANAG 4425 compliant” means “operationally interchangeable” is incorrect for any modern system.

Batch Certification Is Not Transferable

A batch of ammunition cleared for one howitzer type is not automatically cleared for another, even of the same nominal calibre, without additional validation. Batch certification is platform-specific under the three-pillar framework. The operational shortcut of treating any 155mm round as compatible with any 155mm gun — a shortcut that dimensional STANAGs implicitly encouraged — is no longer safe practice.

Fire Control Compatibility Is a Separate Problem

Physical interoperability and fire control interoperability are independent certification requirements. Separate STANAG 4369-series requirements govern inductive fuze setting and fire control data exchange. A round that is physically safe to fire in a given weapon system may still produce inaccurate ballistic solutions if the fire control software is not configured for its specific muzzle velocity profile. WOME practitioners should treat these as two distinct questions requiring two distinct confirmations.

Operational Verification Checklist

For multinational ammunition operations, WOME practitioners should confirm the following before authorising any ammunition-platform combination:

The Standardisation Bodies: Who Owns What

One of the persistent sources of confusion in NATO ammunition interoperability is the number of bodies involved and the overlap between their mandates. The following organisations each hold a piece of the standardisation architecture:

Sources: Body designations and mandate descriptions are drawn from Osman Tasman, “The NATO Ammunition Interchangeability Challenge in the Land Domain”, European Security & Defence, January 2026 (Section 2.4 of the ISC intelligence summary); the NAAG official portal; the CNAD Structure Overview (2012 baseline); and NATO Multinational Capability Cooperation.

The fragmentation is structural, not accidental. Ammunition interoperability spans safety certification (AC/326), technical standardisation (NAAG), operational logistics (NSPA), and military requirements (I-AMMO WG). No single body has the mandate to integrate all four dimensions. The three-pillar framework is an attempt to create coherence across these lanes without reorganising the institutional architecture — a pragmatic approach that works when all three pillars are functioning but leaves gaps when any one pillar lacks resources, data, or political support.

Forward Assessment: Will the Framework Be Enough?

The three-pillar framework is a sound technical response to a real engineering problem. It is more accurate than dimensional standardisation, more adaptable to diverse fleet configurations, and better suited to the high-pressure ammunition types that dominate modern NATO inventories. On its technical merits, the framework is a significant improvement over the STANAG it replaced.

The question is whether it can operate at the scale and speed that Alliance defence requires. Three structural risks stand out.

First, the framework depends on data sharing that nations and industry resist. Pillar 2 weapon clearance trials require ballistic data that manufacturers treat as proprietary. Pillar 3 national operational clearance requires platform-originating nations to share certification data with non-originating operators — effectively disclosing which ammunition they have cleared, under what conditions, and for which barrel variants. Both requirements run against institutional and commercial incentives to restrict information. The digital living AOP-29 faces the same obstacle at a larger scale: its utility depends entirely on nations contributing current, accurate data — and there is no enforcement mechanism if they do not.

Second, the framework is resource-intensive. Dimensional standards are cheap to apply: measure the round, check the envelope, confirm compliance. The three-pillar framework requires live-fire testing (Pillar 2), national certification data maintenance and bilateral sharing (Pillar 3), and national certification infrastructure (Pillar 1). These are expensive, slow processes that require trained personnel and dedicated test facilities. The framework works well for peacetime procurement. Whether it can sustain wartime certification tempo is untested.

Third, the cannon calibre gap is not being addressed at the same pace as platform procurement. NATO nations are fielding 30mm and 40mm systems on a timeline that will outrun any standardisation effort. By the time NAAG LCGLE completes its cannon calibre study, national fleet procurement decisions will have been made. The Alliance risks embedding another generation of interoperability problems into systems that will serve for thirty years.

The recommended forward actions from the source analysis — mutual certification protocols with genuine mutual recognition, digital technologies including AI analysis and blockchain audit trails, multinational testing consortia, integration of Ukraine operational data, exercise-based ammunition exchange trials, flexible industrial framework contracts, and expanded test centre capacity through NATO Regional Test Centres — are all technically sound. They are also all dependent on political commitment and sustained funding from thirty-two nations with competing priorities. The history of NATO ammunition standardisation suggests that technical solutions are rarely the bottleneck. Political will and institutional inertia are.

ISC Commentary

Further analysis pending.