The Essential Elements of Missile Defence – Reflections from the Past, Present and Future

An Essay by COL(RET) Lawrence Lim Teng Chye

When I was studying Systems Engineering at the Naval Postgraduate School (NPS) in 1999, I was particularly intrigued by the nascent concept of missile defence.  Then I was working on a thesis with a group to crystal-ball how future naval warfare might look like in 2030, given that these conflicts would most likely be contested asymmetrically in a VUCA^[1] littoral environment rather than the traditional blue oceans that most conventional navies were built to operate in. 

Fusing a coherent picture in time and space, the foundation of missile defence

Given the wide spectrum of threats that a naval vessel might potentially encounter in the littorals, and the close proximity that these threats would present themselves, defending against these threats (especially against an incoming swarm of high-speed missiles from all directions) seemed an almost impossible task given the short response time required and the need to cover all spatial dimensions with utmost precision.^[2] 

A ship costing several hundred millions of dollars operating in an environment it is not familiar with now runs the risk of being sunk by bad actors using missiles costing several orders of magnitude lower.  This operational conundrum set me to think about how an effective missile defence system might look like and if there would be critical elements governing its design.

To survive an onslaught of incoming missiles, I analysed that the sensors onboard a vessel would need to have the fidelity and update rates required to dynamically differentiate and prioritize targets as the basis to inform interception sequence and means.  As certain frequencies would work better in certain environments and against different classes of targets (due to the immutable laws of physics and geometry), this also means that different types of sensors would need to be used and arrayed in a network to optimise spatial coverage, leverage mutual capabilities and cover each other’s gaps.

To exponentially enhance the effectiveness of this sensor network, these sensors must also work collaboratively not just to fuse a coherent threat picture in time and space, but also to dynamically classify and prioritize targets, recommending the most effective interception measures that are available based on the prevailing Rules of Engagement (ROEs) to system operators, and guiding interceptors adroitly (possibly aided by Artificial Intelligence) to destroy their intended targets before they close-in.  In situations where the threats are homing in at supersonic speeds, every millisecond counts.

By knowing as far out as possible and acting cogently as quickly as possible based on what is permissible at the moment, this could perhaps enable a vessel to neutralise a plethora of incoming threats with very short sense-intercept cycles.  Putting this in today’s layman terms, we would describe such a defence system as multi-dimensional, interdependently layered, knowledge-enabled and being passive reactive.  An example of such a reactive defence system would be the Israel’s Iron Dome; and the Golden Dome that US President Donald Trump in January 2025 directed the Pentagon to build.^[3]

While a well-designed reactive missile defence system may work wonderfully, as evidenced by the Iron Dome in the recent conflict in the Middle East, it is a well-known fact that the Achilles heel of such a system is its own “designed capacity”.^[4]  An adversary can therefore still penetrate the dome by surging threats in space and time, thereby saturating the system beyond its capacity such that it no longer is able to cope.  No dome is therefore impervious and impenetrable, not even an intelligent one.

Furthermore, no system, however well-designed, is ever perfect. One must therefore accept that failures will inadvertently occur, and threats will still somehow leak through despite best efforts and how robust interior lines are.  This would perhaps explain why the reported success interception rate of the Iron Dome is “more than 90%” and not 100%.^[5]  This means that for every 100 incoming threats, up to 10 would invariably leak through and land. 

While it could be easier to deal with the aftermath 10 missiles compared to 100 missiles, one can reasonably question if there is another way to reduce the number of incoming threats by extinguishing the launch potential of the adversary at source. To do this, one would need to have the ability to actively hunt and neutralise the threats (and their support systems) pre-emptively so that they are destroyed before they can fire.  This would effectively take out the threats even before they are able to pose a threat.

This active approach of neutralising the threats at source would theoretically reduce the number of incoming threats and ensure that the designed capacity limit of the reactive missile defence system would never be reached.  Both the active and reactive components of defence must therefore work together to achieve the collective aim of minimising leakers getting through. Between the active and reactive components, one might reasonably posit that the active component is preferred as it physically destroys the launch potential of the adversary to prevent future harm, while the reactive component merely deals with the aftermath of a successful launch.

While this argument is logical and persuasive, actively neutralizing the threats at source requires an operational alchemy par excellence of another league.  It exacts a huge premium on real-time intelligence, planning and execution.  More importantly, it requires one to have the casus belli to legitimize or justify pre-emptive actions to be taken. To overcome the tyranny of range, some capabilities may also need to be pre-positioned forward clandestinely in advance, dramatically multiplying operational risks. The Israeli covert prepositioning of their commandoes deep into Iran to surgically eliminate critical capabilities key of the elite Iranian Republican Guards is a case in point.^[6]  The Ukrainian secret advance deployment of attack drones forward in Russian territory to strike several Russian airbases and installations that occurred on 6 June 2025 is another.^[7]

Moreover, as most of the missile launchers are highly mobile and can hide in “cluttered” environments to prevent their detection and complicate prosecution methods, the actions taken (especially kinetic ones) would also have to consider the potential collateral damage it might cause in the target’s immediate surrounding. Although theoretically expedient, the active component offers no silver bullet as it is beset with its own set of operational challenges that might have grave strategic implications.

On balance, the essential elements of an effective missile defence system must comprise an active as well as a reactive component.  This is true for a ship or vessel.  This also holds true for an area or territory that one is trying to protect.  The active component requires deliberate and laborious planning with execution that could be predicated on certain pre-conditions being met; while the reactive component is technically challenging to implement and sustain but would buy a certain level of insurance.  Both components are resource-intensive and are essentially two sides of the same coin. 

The “missile war” between Israel and Iran in June 2025 illustrates these design elements and operational realities vividly.

With complete air and intelligence superiority over the battlespace, the Israelis were still not able to completely obliterate Iran’s missile launching capabilities even though they could remove key military leaders from the onset and destroy critical “static” military installations. 12 days into the war, missiles continue to be fired by Iran against Israel with no end in sight, destroying infrastructure as well as inflicting deaths and casualties in cities such as Tel Aviv and Beersheba.^[8] 

Strikes conducted by Israel against Iranian missile launchers and ammunition storage facilities have also resulted in collateral damage.  As the deaths on the Iranian side were higher, some have also argued that the Israeli actions were wantonly disproportionate.^[9]  When images of the collateral damage and addendum human suffering were amplified by the media, coupled with the risk that the war might escalate out of anyone’s control, these factors could have perhaps super-charged political pressures for Israel to agree to a ceasefire even when it seemed they had secured the upper hand. 

These developments show that against a determined and thinking adversary that fights elusively and asymmetrically, no amount of conventional superiority would guarantee quick successes, much less decisive outcomes.  Indeed, the Iranian strategy seemed to have moved from exacting retaliation against Israel towards one of conservation after they realized that they had been outgunned. 

By conserving and not losing, it can be observed that the Iranians could still harass Israeli civilians with periodic “potshots” ^[10]to wear them down psychologically, as well preserve precious resources to perhaps stage a comeback and fight another day.  The supposed “stalemate” would also provide fodder in bringing the two parties closer to the negotiating table and settle for political outcomes that would be acceptable for both, albeit with the help of well-meaning third parties behind closed doors.      

Armed with the benefit of hindsight, one can reasonably deduce from the developments in this conflict that possessing an active component is necessary but not sufficient in insulating a country from missile attacks.  Even under the best assumptions, planning and execution (as was the case for Israel), it would be foolish to assume that all stand-off threats can be completely neutralised before they fire thereby rendering the reactive component irrelevant.  The collateral damage arising from kinetic actions against these targets might also erode one’s legitimacy and limit freedom of action in the future. 

Therefore, it is instructive that the discourse should not be centred on the primacy of the components but on the operational synergies that both would collectively deliver.  Like a warrior wielding a spear and a shield into battle, the active and reactive components of missile defence must work hand in glove and in harmonic unison.  Depending on the prevailing strategic context and operational tempo, the warrior’s reliance on the spear and the shield to achieve his objectives would need to be adapted and shifted dynamically.

Given that there would always be leakers, even for the “best” missile defence system, it becomes pertinent to further improve the shield as a bulwark against asymmetric strategies, to facilitate civil-emergency response and to sustain the will of the people to prevail under prolonged attacks.

The stand-off threats of today do not just comprise conventional missiles that are governed by the principles of gravity and ballistics.  They also include “new age” munitions such as killer-drones that can operate in collaborative swarms that can fly in pre-programmed flight profiles or navigate by terrain.^[11]These munitions can be produced en-masse and in relative quick-time.  They are also several orders of magnitude cheaper than the expensive interceptors used in missile defence systems such as the Iron or Golden Domes.^[12] 

The wide availability of stand-off attack means would allow prospective adversaries the asymmetric option of using cheaper systems to first probe and test the defender’s shield and deplete its stock of interceptors, before sending the “heavy cavalry” in subsequent waves to penetrate and cripple one’s defence.  This might perhaps explain why the Iron Dome was less effective in dealing with the heavier ballistic missiles that were lobed into Israel by Iran in the later days of the war, while enjoying good interception rates during the initial days.^[13]

In this regard, the shield must be improved in three aspects: Firstly, it must have the added fidelity to dynamically distinguish between new classes of threats and emergent ones even in a combined swarm attack scenario. Secondly, it must have the intelligence to dynamically program the most appropriate interception mix to effectively negate the incoming threats.  Thirdly, the repertoire of interception means must be increased so that one does not end up using one type of expensive interceptor against all classes of targets.  Indeed, against a wider spectrum of threats, the “toolbox” of interception means (including non-kinetic options) must grow commensurately to provide cheaper options and dismantle an adversary’s asymmetric operational designs.

To manage the leakers, the sensors must also bridge the military-civil nexus by predicting the impact points with sufficient accuracy to reliably localize warning and guide the safe evacuation of residents.  The high economic costs arising from civil disruption simply means that it would not be tenable to cease all economic activities during every missile attack.  Apart from the blunt use of sirens, affected residents can also use mobile apps to receive real-time life-saving information such as the assessed time to impact and receive directions to the nearest shelter within their immediate vicinities. Such information would also be useful to direct and prioritise civil-emergency response to the affected sites which must include medical, urban rescue, fire-fighting and psychological support agencies.^[14]

The last point on psychological support needs to be heavily underscored.  As the steel of a country is dependent on the collective will of its people, sustaining this will to fight and resist would be paramount, especially in a protracted “tit-for-tat” scenario. ^[15] At the end of the day, the civilian populace must feel that they would be well taken-care off; and have the support and resources to prevail.  Seen from this perspective, in addition to the active and reactive components, an effective missile defence system must be extended to also encompass high quality civil-emergency response so as to sustain the will of the people that are under attack.  

In summary, these are the three essential elements of a missile defence system that must work collectively in harmony: the active, reactive and civil-emergency response components.  The missile and drone age is now upon us, and future conflicts would be fought using a preponderance of stand-off means that are highly flexible, cheap and readily adaptable.^[16]  To build up the three essential elements systematically, planners would need to consider reorganization of existing structures to prioritise as well as synergize capability development across portfolios to balance resourcing realities; foster and promote collaboration across stove piped military-civilian branches; and establish mechanisms to strengthen operational learning through joint military-civil exercises to continually robust response plans. 

Planners have the work cut out for them. But this work is definitely worth doing to safeguard a future that has already arrived!

[1] This is an acronym for Volatile, Uncertain, Complex and Ambiguous (VUCA). For more background about VUCA, refer to Nate Bennett and G. James Lemoine, “What VUCA Really Means for You”, Harvard Business Review, January – February 2014, https://hbr.org/2014/01/what-vuca-really-means-for-you.

[2] The System Engineering & Integration Curriculum, “Crossbow Project”, Naval Postgraduate School, March 2002, https://nps.edu/documents/103424733/107333271/execsummary+v2.pdf/353f4b8c-ba53-43c5-b20a-6a2260ac2754.

[3] President Donald J. Trump, Executive Order of the White House, “The Iron Dome for America”, 27 January 2025, https://www.whitehouse.gov/presidential-actions/2025/01/the-iron-dome-for-america/.

[4] Patrick Sullivan and John Amble, “What Happened to Iron Dome? A Lesson on the Limits of Technology at War”, Modern War Institute at Westpoint, 10 October 2023, https://mwi.westpoint.edu/what-happened-to-iron-dome-a-lesson-on-the-limits-of-technology-at-war/.

[5] The Economic Times, India Times, “Cracks in the Dome. How Strong is Israeli’s Iron Defense Now?”, 14 June 2025, https://economictimes.indiatimes.com/news/defence/cracks-in-the-dome-how-strong-is-israels-iron-defense-now/articleshow/121844325.cms.

[6] The TWZ Newsletter, Thomas Newdick, “Israeli Commandos Attacked Iranian Air Devenses With Drones From Inside The Country: Report”, 13 June 2025, https://www.twz.com/air/israel-hid-drones-missiles-around-iran-to-target-nuclear-facilities-and-more-report; and Onmanorama, “Israel confirms commandos operated inside Iran during 12-day war; Mossad thanks CIA”, 26 June 2025, https://www.onmanorama.com/news/world/2025/06/26/israeli-commandos-iran-operations-cia-mossad.html.

[7] The New York Times, “Ukraine Says It Unleashed 117 Drones in an Attack on Russia: What to Know”, 2 June 2025, https://www.nytimes.com/2025/06/02/world/europe/ukraine-russia-drone-strike-what-to-know.html.

[8] Emanuel Fabian, The Times of Israel, “The Israel-Iran war by the numbers, after 12 days of fighting”, 24 June 2025, https://www.timesofisrael.com/the-israel-iran-war-by-the-numbers-after-12-days-of-fighting/.

[9] United Nations News, Global Perspective Human Stories, “UN warns of mounting humanitarian toll as Israel-Iran hostilities continue”. 19 June, https://news.un.org/en/story/2025/06/1164616.

[10] BBC News, “Iran missiles cause multiple casualties after strikes in Israel”, 13 June 2025, https://www.bbc.com/news/live/c93ydeqyq71t.

[11] C.J. Chivers, “The Dawn of the AI Drone”, New York Times, 5 January 2026, https://www.nytimes.com/2025/12/31/magazine/ukraine-ai-drones-war-russia.html.

[12] Michael J. Boyle, “The Drone Age: How Drone Technology Will Change War and Peace”, pages 12-24, Oxford University Press 2020.

[13] Sam Lair, “Shallow Ramparts: Air and Missile Defenses in the June 2025 Israeli-Iran War”, Foreign Policy Research Institute, 17 October 2025, https://www.fpri.org/article/2025/10/shallow-ramparts-air-and-missile-defenses-in-the-june-2025-israel-iran-war/.

[14] The author notes that Singapore has also implemented a similar system called the Cell Broadcast System to “quickly alert members of the public and relay emergency messages to their phones”. More information can be found in the CNA news article at https://www.channelnewsasia.com/singapore/emergency-alerts-phones-cell-broadcast-system-scdf-disaster-management-relief-asean-5304051.

[15] Ben Connable et all, “Will to Fight - Returning the the Human Fundamentals of War”, RAND Corporation, 13 September 2019, https://www.rand.org/pubs/research_briefs/RB10040.html.

[16] James Roger, “Future Threats: Military UAS, Terrorist Drones, and the Dangers of the Second Drone”, A Comprehensive Approach to Countering Unmanned Aircraft Systems, January 2021, https://www.japcc.org/chapters/c-uas-future-threats-military-uas-terrorist-drones-and-the-dangers-of-the-second-drone-age/.