Image Source: Militarnyi
Russia’s invasion of Ukraine underscores a dire reality –conventional military conflicts are resurging globally without prospects for abatement. The deterioration of the security landscape should move the United States to rethink its kinetic deterrence capabilities. While the United States retains the world’s premier fighting force, a lack of magazine depth – the number of munitions stored in peacetime – afflicts its conventional deterrence posture. The United States should expand its magazine depth to strengthen deterrence swiftly and effectively, particularly for systems likely to play crucial roles in modern conventional conflicts.
A cannon without ammunition is just an expensive piece of metal. Moreover, a cannon that can only fire once becomes an expensive piece of metal. The ability to wage a protracted war hinges centrally on the capacity to keep the guns firing. The amount of munitions available, the magazine depth, play a crucial role during wartime and in preparation for armed conflict. A nation seeking to prepare an effective defense should thus not only field modern and well-equipped armed forces but also ensure that sufficient stocks of all required munitions are available. In addition, sufficient industrial replenishment capacities must exist to restock the arsenals during any potential conflict.
To effectively deter an adversary, a nation must be able to enforce the threats whereupon the deterrence strategy is based. Lacking magazine depth undermines this credibility. If the U.S. stockpiles of ammunition only support a limited time of intensive, potentially peer-to-peer combat, adversarial actors may estimate that if they can sustain combat beyond this limited time, their objectives can be achieved, and American deterrence can be challenged.
Mark Milley, then chairman of the Joint Chiefs of Staff, testified to Congress in March 2023 and told lawmakers that the United States has a long road ahead in ensuring that sufficient ammunition is available. Both insufficient domestic production and the direct and indirect involvement of the United States in several conflicts severely depleted the arsenals. The war in Ukraine saw enormous quantities of U.S. artillery shells, small-arms munitions, air defense missiles, ATGMs, and other equipment transferred to the Ukrainian Armed Forces. This demonstration of the intensity of symmetric war and the resulting consumption of vast amounts of material highlights not only the urgency of improved conventional deterrence but also the sheer quantity of equipment consumed by modern war. Unfortunately, at the expense of the Ukrainian people, this insight is now reified in policy circles in Washington, with military officials such as Milley ringing the alarm bells.
Lacking magazine depth constitutes a critical national security challenge for the United States. In their current state, American arsenals are unlikely to support protracted and full-scale engagements. This is especially concerning given the rising geopolitical tensions and the concomitant uncertainty. U.S. Department of Defense officials have repeatedly voiced their concerns about this gap in the American security posture. Ukraine is imperative to the United States for ideational and grand-strategic reasons. However, when examining material interests, there are regions and choke points of superior interest to the United States: the Strait of Hormuz, the Malakka Passage, and the semiconductor factories in Taipei. While this list is not exhaustive, it does illustrate that the United States is confronted with critical vulnerabilities. The global interconnectedness of the economic system and America’s continued reliance on international trade and open sea lanes mean the growing instability around global choke points directly threatens America’s vital interests. Recent attacks on vessels in the Red Sea by Houthi forces are but one example of this relationship. Globally intertwined markets have created profound interdependencies. Thus, the ‘Deep Engagement’ strategy will unlikely change over the foreseeable future, even in an age of domestic upheavals. The United States will face pressures in several theaters and thus must be able to deter a range of adversaries simultaneously. Should this deterrence fail, America may be embroiled in multiple high-intensity conflicts. Both these scenarios require a strengthened posture, and expanding magazine depth is critical to achieve this goal.
So what should be on the United States wish list? Firstly, the 155mm artillery shell, NATO’s standard caliber shell, is used on most Western artillery systems. It has become symbolic of the American magazine shortages. Furthermore, the ‘155’ is widely used by non-NATO countries like South Korea, and as such, bound to feature in most future contingencies, even those without direct American involvement. A second category of essential systems are light anti-armor guided missiles, including the FGM-148 Javelin or Spike NLOS. Such platforms have proven invaluable, and in Ukraine, they played a critical part in defeating the Russian forces in the first stage of the full-scale invasion. The third systems category is anti-air missiles, both surface-to-air and air-to-air variants. These include the PAC-3 missiles for the Patriot, the AIM-120 AMRAAM, which is both air and ground-launched, and the SM-6, a ship-launched multirole missile. Any modern conventional conflict will involve aerial threats, and to protect civilian areas, military bases, and other assets such as surface ships, an abundance of effectors will be necessary to defeat such airborne threats. Finally, the United States should seek to increase its stock of long-range fires, such as the Tomahawk or the JASSM, as they can strike high-value targets well inside hostile territory.
A concerted effort to increase the stockpiles of these systems will almost immediately improve deterrence, allow swift implementation, strengthen the defense-industrial base, and leverage established interoperability. First, expanding arsenals increases the potency of the United States’ deterrence posture. This course of action signals to friends and foes alike that the United States can support combat operations in multiple theaters and contingencies. In addition, should deterrence fail for exogenous reasons, expanded magazine depth would provide the necessary means for any protracted conflict. Furthermore, the United States would not only be capable of maintaining operations itself but also be able to lend increased support to its allies without jeopardizing the minimally required magazine depth. Hence, expanded stockpiles also mean greater leeway to support allied forces in case conflicts arise.
Second, increasing the United States magazine depth can be implemented relatively quickly, especially vis-à-vis the alternative of procuring entirely new systems or expanding the size of the armed forces. The necessity to command sufficient productive capacities is not new. However, it has regained urgency in the wake of the Ukraine war. Congressional actions have demonstrated that production capacity, especially for comparatively simpler deliverables such as 155mm shells is readily expandable if political willingness exists. However, more complicated and technology-laden munitions such as cruise missiles, air defense missiles, or precision-guided munitions come with significantly more profound challenges for increased procurement. This duality is visible in the FY2024 National Defense Authorization Act, as budgetary approvals for systems such as JASSM or the SM-6 did not increase compared to prior levels. Put differently, the Pentagon did not take the initial steps towards a significantly increased magazine size. Nonetheless, a steady increase over time and clear signals to the defense industry can ensure that production rates increase and magazines are equipped with sufficient quantities of pertinent equipment, even with ongoing contingencies in Ukraine, Israel, or around the Gulf of Aden.
Third, focusing on a permanently expanded magazine depth would strengthen the defense-industrial base by making long-term commitments to the production of defense equipment, enabling the overall expansion of the workforce. Several systems, such as the AIM-120, are already produced at maximum capacity (around 500-800 missiles annually). Investing in magazine depth would incentivize private defense firms to expand production lines. This increased base production capacity complements the deterrence strategy by creating the latent possibility of dramatically increased production volumes should a conflict break out. In essence, an adversary would then have to contend with a higher immediate availability of munitions and an improved replenishment rate.
Finally, the United States may leverage the productive capacities of allied nations to expand magazine depth, given that allies and partners use the same ammunition calibers and system types. The ‘155’ is the best example, as this caliber is the standard on every NATO artillery system and a wide range of international platforms, such as the M109 variants, the British AS-90, the German PzH 2000, or the Swedish Archer. The 155 is produced in various countries, which allows the United States to work with allied nations to stock the reserves of munitions. The recent U.S. procurement of half a million shells from South Korea demonstrates the viability of this proposition. However, a vast majority of the pertinent systems are manufactured solely in the United States hence purchasing foreign countries’ ammunition should be paired with a strengthened domestic defense-industrial base. Permanently expanding magazine depth is more necessary than ever to strengthen American deterrence. Russian imperialism is unlikely to disappear from the world stage. Volodymyr Vakhitov and Natalia Zaika, tenured professors at the Kyiv School of Economics, labeled it the foremost threat to global security. Baltic military officials are pessimistic about the time it will take Russia to reconstitute after Ukraine and invade more countries. Other global flashpoints are sweltering, and the potential for conflict is salient. Filling the “arsenal of democracy” may become more necessary than ever to safeguard American interests at home and abroad. Naturally, expanding arsenal stocks should be considered part of a broader effort to strengthen force readiness and bolster deterrence. Nonetheless, bolstering magazine depth is a vital first step in enhancing American conventional deterrence.