The Air Defense Artillery needs to be all that it can be. It can ill afford to maintain a single, unintegrated system as an Army of one, writes Tom Karako of CSIS.

The US Army owns two Iron Dome batteries. (US Army)

For several years the US Army has been experimenting with Israel’s Iron Dome system. In the following op-ed, Tom Karako of the Center for Strategic and International Studies argues that Iron Dome does not match the Army’s needs, and that it may be time to move on.

This week, senior US Army leaders are gathering in Huntsville, Alabama for the annual Global Force symposium, hosted by the Association of the US Army. They do so amid increased budget pressure on the service reflected in the fiscal 2024 budget request, challenges for their end strength outlook, and recruiting shortfalls.

One important topic of conversation should be whether Iron Dome still belongs in the Air Defense Artillery branch’s force structure, and if not, what to do with it. An objective review of the situation yields a straightforward conclusion: Iron Dome is a great capability, but not one that fits the US Army in this decisive decade. It is time to evaluate alternatives, including giving it to another country, transferring it within the US military, and sending it back to Israel.

The Iron Dome system is highly effective against the threats it was designed to contend with: rockets, artillery, mortars, and slower-flying cruise missiles. With over 2,000 claimed intercepts, it is among the most combat-proven air defenses in history. Its capability is greatest when operationally integrated as part of a layered defense, as it is deployed in Israel. As a defense acquisition program, Iron Dome is a remarkable case study in urgent material development, cost-effective interceptors, and multi-national development, financing, and production.

Defending against the threat of cruise missiles, at the higher end of Iron Dome’s capability, is of particular concern to the United States. As seen in Ukraine, cruise missiles have become what John Plumb, the first Assistant Secretary of Defense for Space Policy, calls “weapons of choice.” Their characteristics and proliferation present the joint force with a severe capacity and manning shortfall to defend forward bases, including airbases on Guam and elsewhere.

The Army has been trying to get new cruise missile defense capabilities since 1993, with numerous stops and starts. In 2018, fed up with the lack of progress, Congress required the Army to acquire some kind of interim solution. Those who had drafted the statutory provision might have supposed it would be used to get a system like NASAMS, which today defends Washington, DC and is being successfully employed in Ukraine against Russian cruise missiles. The next year, Army Chief of Staff Gen. Mark Milley approved the purchase of two Iron Dome batteries, with an option for more.

In many quarters, the Army’s acquisition of Iron Dome, against the counsel of some senior air defense leadership at the time, came as something of a surprise. Even before they were delivered in 2020, it was clear that they were unlikely to fit in the future force, and that the future option would not be exercised. Soldiers were trained to operate the system, it was briefly tested on Guam, and it has since been sent to Joint Base Lewis-McChord, in Washington State.

While the Iron Domes were being acquired as the interim capability, the Army held a separate competition for an enduring solution to counter drones and cruise missiles. The program of record, called Indirect Fires Protection Capability (IFPC), includes both kinetic and nonkinetic capabilities. The non-kinetic component includes lasers and high-powered microwaves. For the kinetic interceptor competition, the Army held a shoot-off between one launcher with AIM-9Xs and another launcher with a variant of the Tamir (the interceptor used by Iron Dome), called Skyhunter. Following the shoot-off, the Army selected the AIM-9X offering for what is known as Enduring Shield. While AIM-9X is the only interceptor currently programmed for the IFPC launcher, in the future it will support multiple types. In principle, a Tamir variant could be among them.

Further demand for cruise missile defenses will come with the defense of Guam, with last year’s designation of the Air Force as lead service for homeland cruise missile defense, and by the Army’s pursuit of a future supersonic cruise missile interceptor for IFPC. Given this demand, these much-awaited IFPC capabilities cannot arrive soon enough.

The Problem

If the Air Defense Artillery needs all the capacity it can get, why not keep Iron Dome?

The simple problem is that Iron Dome, designed as part of Israel’s layered air defense network, cannot currently be integrated into the US Army’s future air defense brain, the Integrated Air and Missile Defense Battle Command System (IBCS). Unless or until granted access to the underlying source code, cybersecurity concerns preclude that from happening. For better or worse, a requirement to plug into IBCS applies to virtually all new and legacy systems, including Patriot, Sentinel and LTAMDS radars, and IFPC. The requirement imposes costs on both these forthcoming systems and, in time, on other allies, such as the sixteen or so other operators of Patriot who will continue to use its organic command and control system, rather than getting IBCS.

Cyber uncertainty is why Army leadership has consistently made clear that it cannot integrate Iron Dome into its future force. Unless Israel permits access to address these concerns, these two batteries will remain a standalone, niche capability. As such, the Army seems to not know what to do with them. Despite the attention given to air and missile defense for Guam, INDOPACOM appears to have no intention of stationing Iron Dome within a thousand miles of that island, at least not unless war breaks out.

These technical difficulties do not diminish the engineering marvels of Iron Dome and its several elements. Numerous nations, for instance, are pursuing or have acquired its radar. There is likewise nothing wrong with its capable and cost-effective Tamir, or for that matter Tamir-like, interceptors. Should an American-made Iron Dome-like system be acquired by the Army, many of these problems could go away. The potential for further US-Israel cooperation on air defense munition coproduction seems strong. These bright prospects for future programs are distinct from the original batteries, which will remain stovepiped.

In principle, the two batteries could be operated in a standalone manner. In practice, this guarantees considerable expense with marginal return. Retaining two batteries of a single system, as opposed to twenty, carries a daily tax of opportunity costs measured in sustainment, force structure, training, deployment flexibility, and other scarce resources that cannot be applied to the rest of the ADA.

Personnel is one especially scarce and important resource. To crew the Iron Dome batteries, soldiers had to be pulled from the forthcoming eighth THAAD battery. The Army has prudently begun to expand ADA force structure, especially for IFPC, and with an additional Patriot battalion. But the number of air defenders will still fall far short of need. The operational tempo of the ADA, especially Patriot units, has long been among the highest in the joint force. Other examples of the branch’s personnel needs are not hard to find.

With last year’s defense bill, Congress signaled the potential need for still further Patriot capacity. In 2012, the objective requirement for THAAD batteries was set at nine, but only seven are currently operational, meaning that the Kingdom of Saudi Arabia could soon have more THAAD firing units than the United States of America.

The utility of scale, integration, and layering applies to air defenders of all nationalities and air defense systems of all types. The ADA needs to maximize the return from every air defender and piece of equipment in the branch. It cannot afford to devote personnel to train, operate and maintain two systems that by all accounts do not fit into its force structure. Given the increasing threat, the unmet integration criterion, and the need to most effectively employ every air defender, a reasonable conclusion is that the time has come for the US Army to begin divesting Iron Dome from its operational force.

Possible Next Steps

What, then, should be done with the Army’s two batteries of Iron Dome? Besides storage, at least three courses of action are worth consideration.

One option is to give them to Ukraine as part of a drawdown of US capability. Iron Dome could be usefully employed against lower-tier Russian threats, like those supplied by Iran, which have been used extensively against civilian targets — much like the threat Iron Dome was created to combat. Such a step would boost Ukraine’s air defense capacity, add to a layered defense, and preserve other scarce and more costly interceptors, including NASAMS, HAWK, and Patriot.

Any third party transfer would require permission from the government of Israel, whose foreign policy towards Russia has thus far precluded military aid to Ukraine, to include air defenses and even other nations’ Spike anti-tank weapons made under licensed production. (Similar drama has been seen with Swiss and German reluctance to approve third party transfers to Ukraine.) Assuming Israeli approval for Ukraine remains foreclosed, approval could also be requested to send or sell them to one of the many other allies and partners considering Iron Dome, or perhaps offer them as an extended loan to some other European country who has lent their air defenses to Ukraine.

Again, standalone capability may be sufficient if tight integration is not required. Integrated fire control is not needed in situations where fire direction and interoperability are good enough. Nevertheless, the several Scandinavian and Baltic countries reportedly considering Iron Dome and David’s Sling could anticipate facing a quandary similar to that of the US Army if they were to propose adding those systems into the NATO Integrated Air and Missile Defense System (NATINAMDS) architecture, as opposed to operating them organically as national assets. So might Germany, if it acquires Arrow-3.

A second category of alternatives, transfer within the US military, would include harvesting the Tamir interceptors and giving them to the US Marines. For their Medium Range Intercept Capability (MRIC) program, the Marines finessed the integration problem by pairing the sturdy Tamir with their own command and control system, their own Ground/Air Task Oriented Radar (G/ATOR), and a modified, expeditionary launcher. A related alternative would be to designate one or both batteries as a joint Army-Marines asset at White Sands Missile Range for training or concept development. Still another option is to give the Iron Domes to a National Guard unit on Guam  or elsewhere. This last path, circumventing the regular Army’s IBCS requirement, would help alleviate regular force structure within the ADA while accepting the limitations of fire direction.

A third course would be to give the Iron Dome batteries back to Israel as part of the annual missile defense aid package from the United States. The usual contribution to Israeli missile defense of $500 million per year rose to $1.5 billion in 2022, due to a $1 billion boost specifically for Iron Dome procurement. The long-running and productive US-Israel partnership on missile defense will continue to bear fruit for decades to come, including with higher-end development programs like the forthcoming Arrow-4.

To avoid divestment, it may be worth one final, formal request to Israel to permit source code access and whatever else is necessary to fully address the cybersecurity concerns and integrate the batteries. Barring this resolution, however, it seems necessary to conclude that the Army’s experiment with Iron Dome has served its purpose, and move on. It would be no indictment of Iron Dome to do so. The long list of terminated ADA programs is a respectable reminder that not every air defense experiment persists.

In line with the Army’s new branding, the Air Defense Artillery needs to be all that it can be. It can ill afford to maintain a single, unintegrated system as an Army of one.

Tom Karako is the director of the Missile Defense Project at the Center for Strategic and International Studies.

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