The US Army has decided to halt plans to replace the Patriot missile system, choosing instead to enhance the PAC-3 Missile Segment Enhancement (PAC-3 MSE) interceptor. This decision, revealed during the Association of the United States Army’s (AUSA) annual conference, follows a recognition of the high costs involved in a full replacement of the system.
The move to upgrade the Patriot PAC-3 MSE is aimed at addressing evolving threats from hypersonic missiles and other advanced weapon systems expected in the coming decades, as well as managing operational costs. The PAC-3 MSE has demonstrated effectiveness in real-world conflict scenarios, including intercepting Russian hypersonic missiles in Ukraine, but challenges remain, particularly regarding its ability to handle saturation attacks.
This shift in strategy reflects broader concerns about the future landscape of missile threats and the importance of integrated, flexible defense systems. The US Army’s Integrated Air and Missile Defense (IAMD) system, including advancements in its Integrated Battle Command System (IBCS) and Lower Tier Air and Missile Defense Sensor (LTAMDS), will continue to evolve, focusing on improving the performance of the PAC-3 MSE while seeking tighter integration between various missile defense platforms like Terminal High Altitude Area Defense (THAAD) and Patriot.
The PAC-3 MSE has made headlines for its successful performance in Ukraine, particularly against Russian hypersonic missiles. In May 2023, the Ukrainian military, operating US-supplied Patriot systems, intercepted six Russian Kinzhal hypersonic missiles over Kyiv. This was seen as a significant triumph for the PAC-3 MSE, which employs a hit-to-kill mechanism, meaning that it destroys targets by colliding with them at high speed rather than relying on explosive warheads.
However, despite these successes, some analysts argue that the Kinzhal’s limitations may have played a role in its vulnerability. Peter Mitchell, in a May 2023 article for the Modern War Institute, explains that while most hypersonic missiles rely on advanced propulsion systems like scramjets for sustained speed and maneuverability, the Kinzhal uses a solid-fuel rocket engine. This design choice raises doubts about the missile’s ability to maintain hypersonic speeds throughout its flight, particularly in its terminal phase, which may explain why it was intercepted by the PAC-3 MSE.
Mitchell compares the Kinzhal to a “giant lawn dart,” noting that it lacks the agility and advanced maneuverability expected from other hypersonic weapons. While the PAC-3 MSE can effectively intercept such missiles, its limitations become apparent in other scenarios, especially against more sophisticated and numerous threats.
The PAC-3 MSE is its ability to defend against saturation attacks, where a large number of missiles are launched simultaneously to overwhelm air defense systems. While the PAC-3 MSE excels in precision interception, its high cost—at approximately $3.7 million per interceptor—combined with extended production times of up to 20 months, makes it a less feasible option for handling mass missile barrages.
In Ukraine, the Patriot system’s deployment near the front lines has exposed vulnerabilities. In May 2023, Russian forces successfully targeted and destroyed two US-made Patriot missile launchers, a control station, and a radar with an Iskander ballistic missile in Ukraine’s Dnipropetrovsk region, according to Russian state media outlet TASS. This incident highlights the risks of placing valuable and high-cost missile defense systems in vulnerable positions near the battlefield, where they can be detected and attacked.
Russia’s reconnaissance-strike capabilities have evolved, as noted by Viktor Bodrov in TASS, enabling better identification and targeting of air defense assets. The destruction of these systems suggests that while the PAC-3 MSE and Patriot systems can successfully intercept hypersonic missiles, their ability to withstand a concerted and prolonged attack is far from guaranteed.
To mitigate some of these challenges, the US Army is focusing on greater integration between its various missile defense systems. This includes efforts to enhance coordination between THAAD and Patriot systems, which would allow the simultaneous use of both platforms’ interceptors against advanced threats.
In the Indo-Pacific theater, the Missile Defense Agency (MDA) has already begun testing this integration, showcasing the potential benefits of tighter coordination. In a region where missile threats from countries like China are a growing concern, this approach aims to streamline battle space management and ensure a more efficient response to advanced missile threats.
China’s missile capabilities represent a significant and growing threat to US military assets, particularly in the Indo-Pacific. China’s DF-21D “carrier killer” and DF-26 “Guam killer” missiles, both designed to target naval and land-based assets, feature maneuverable warheads and long ranges. These missiles are part of China’s broader anti-access/area denial (A2/AD) strategy, which seeks to keep US forces at bay and limit their freedom of movement in the region.
According to experts, China might also exploit vulnerabilities in the US missile defense “kill chain” by launching simultaneous attacks across multiple domains, including cyber and space, alongside missile strikes. This complex, multi-domain warfare strategy would require the US to adopt more sophisticated and integrated missile defense systems, further emphasizing the importance of the PAC-3 MSE and the need for coordination between THAAD and Patriot.
The US military’s global commitments, particularly in supporting Ukraine and Israel, are putting additional strain on its air defense resources. For instance, recent deployments of Patriot systems to Ukraine, coupled with the decision to send a THAAD missile battery to Israel, have led to delays in modernizing other missile systems.
As the Associated Press (AP) reported, these moves have stretched the US Army’s resources thin, impacting its ability to train and maintain troops at home. The frequent deployments of air defense units have also reduced the amount of time systems spend in depots for necessary upgrades and maintenance, exacerbating the problem. This strain could prove especially problematic in the Indo-Pacific region, where China’s missile capabilities significantly outmatch those of Russia or Iran.
The Council on Foreign Relations (CFR) also recently highlighted that despite successful missile defense operations, such as Israel’s neutralization of Iranian missile attacks with US support, increasing missile sophistication and frequency could soon overburden air defense systems. This situation underscores the need for continual modernization of US missile defense systems and further integration between platforms like Patriot and THAAD.
The high cost of maintaining and upgrading systems like the PAC-3 MSE, as well as the potential for delays due to overstretched resources, points to a broader strategic dilemma for the US. As adversaries such as Russia and China continue to develop more advanced missile systems, the US may need to reconsider its missile defense posture.
Experts have suggested that rather than focusing on denial-based strategies—such as building more interceptors to stop every potential missile—Washington may need to adopt a deterrence-by-punishment approach. This strategy would prioritize imposing costs on adversaries through retaliatory measures, such as economic sanctions or precision strikes, rather than relying solely on missile defense systems to block incoming threats.
Melanie Sisson argues that deterrence by punishment might be more practical when dealing with advanced adversaries like China. Attempting to deny China’s military objectives, particularly in a conflict over Taiwan, could be risky and provoke escalation into a full-scale war. Instead, by threatening severe retaliation, the US could deter aggression more effectively without needing to intercept every missile launched by an adversary.
The decision to enhance the PAC-3 MSE interceptor instead of replacing the Patriot system reflects the US Army’s recognition of both the effectiveness and the limitations of its current missile defense assets. While the PAC-3 MSE has shown promise in intercepting hypersonic missiles, particularly in Ukraine, challenges remain in defending against saturation attacks and managing the high costs associated with the system.
As missile threats from countries like Russia and China evolve, the US Army’s strategy will likely continue to focus on tighter integration between defense platforms like Patriot and THAAD, while considering broader deterrence strategies. The shift from a denial-based approach to one emphasizing punishment and retaliation could shape the future of US military doctrine in the face of increasingly sophisticated missile threats.
