The U.S. Navy plans to move ahead with the introduction of Lockheed Martin’s Patriot Advanced Capability-3 Missile Segment Enhancement (PAC-3 MSE) missile into its arsenal of missiles aboard its Aegis vessels.
In a statement to Reuters, industry officials confirmed that the integration effort was driven by advances in Chinese ballistic and hypersonic missile technologies.
The PAC-3 MSE, which is the latest missile in the PAC-3 family, provides terminal ballistic missile defense against short to medium-range ballistic missiles. The missile is utilized by the U.S. Army and has been approved for sale to 16 international customers.
Efforts to integrate PAC-3 missiles into Aegis ships go back many years. Lockheed Martin conducted a Navy-funded feasibility study for a sea-based version of the PAC-3 Cost Reduction Initiative (CRI) to be launched from the MK 41 Vertical Launch System (VLS) back in 2004. The missile was intended to fill the terminal interception gap left by the cancellation of the Navy Area Ballistic Missile Defense Program in 2001.
In 2008, the Missile Defense Agency (MDA) initiated a limited competitive program between Raytheon’s Standard Missile 6 (SM-6) and Lockheed’s PAC-3 MSE. The aim of the program was to procure a potential future interceptor that could be utilized by Navy vessels for terminal defense against ballistic missiles. This new missile was intended to eventually succeed a number of Standard Missile 2 Block IV (SM-2 BLK IV) missiles that were modified to provide interim terminal defense..
However, the MDA selected a modified variant of the SM-6 for this terminal role, which intercepted its first ballistic missile target in July, 2015.
Moving past this setback, Lockheed Martin continued to pitch the PAC-3 missiles as naval interceptors to potential customers, including the U.S. Navy, but there was little interest from the Navy’s side.
During the 2023 Surface Navy Association Symposium, the company announced for the first time that it was doing testing and integration work on the missile to make it compatible with the Aegis Combat System which hinted at some potential interest for the missiles.
Lockheed has self-funded the effort to integrate the PAC-3 missiles with the Navy’s surface vessels. Which, according to Lockheed, involved modifications to the missile’s data link receiver so it could communicate with the SPY-1 radar. This is because the principal communication bands the MSE uses are C and X band, while the SPY-1 radars aboard Navy vessels work in S band.
The first launch of a PAC-3 MSE out of a MK 41 VLS took place in May 2024. The company used the MK 70 Payload Delivery System as a launch platform and Virtualized Aegis to communicate with the missile.
Augmenting Existing Layers
The Navy’s Aegis ships utilize three missiles for ballistic missile defense: the Standard Missile 3 Block IIA, the Standard Missile 3 Block IB, and the Standard Missile 6 Dual I/II.
The first SM-3 missiles intercept their targets outside the atmosphere in what is known as “exo-atmospheric intercept”, while the SM-6 intercepts targets inside the atmosphere which is also called “endo-atmospheric”. Together, these missiles provide a three layered defense system against intermediate to short range ballistic missiles.
Ever since the MDA picked the SM-6 as the new terminal interceptor, the missile has been modified to better optimize it for this new role. Thanks to these modifications, the SM-6 has demonstrated a good track record in testing, with the missile intercepting seven out of nine ballistic missile targets.
While the SM-6 continues to demonstrate a good track record, it has done so mostly against more simple ballistic missiles. On the other hand, the PAC-3 family of missiles are better optimized and have been more rigorously tested against ballistic and maneuvering missile threats.
What makes PAC-3 a better choice for countering these threats is the missile’s usage of Hit-To-Kill (HTK) mechanism to destroy threats. Unlike most existing surface to air missiles, which utilize explosive warheads that detonate in close proximity to their targets, the PAC-3 missiles make body-to-body contact with the incoming threat at high speeds.
The kinetic energy generated from the two missiles colliding with each other destroys both of them in the process.
Moreover, the SM-6 utilizes traditional aerodynamic control surfaces, which provide worse maneuverability at higher altitudes. On the other hand, the PAC-3 missiles utilize aerodynamic control surfaces that are augmented by 180 miniature rocket thrusters located at the front of the missile.
These miniature rocket motors provide better fine tuning at higher altitudes than aerodynamic control surfaces. Thus allowing the missile to have the control authority it needs to make a HTK intercept.
Together, these unique design features and a rigorous test program have made the PAC-3 MSE into an exceptional interceptor missile. This was reaffirmed last year when the missile intercepted Russia’s vaunted AS-24 Killjoy (Kh-47M2 Kinzhal) hypersonic missile during a Russian missile attack on Ukraine.
Additionally, due to increased international demand, Lockheed Martin and subcontractors are working towards increasing yearly production of PAC-3 missiles from 550 to 650 a year by 2027. Lockheed has opened new production facilities and brought on multiple subcontractors in Poland and Spain. Japan, which also produces PAC-3 missiles locally, is set to increase yearly production from minimum sustainment levels of 30 missiles to 100 missiles a year.
On the other hand, SM-6 production has hovered at about 125 missiles a year. The Navy has funded an increase in SM-6 production from the current 125 missiles to 200 by 2026 and 300 by 2028. However, this is going to be substantially below the 750 PAC-3 MSEs that will be produced yearly by 2025.
As such, the Navy integrating PAC-3 into Aegis vessels would allow it to tap into this stable production line that will be producing 750 missiles a year and all the price advantages that will come with it.
Growing Interest
While Lockheed has entirely self-funded modifications and testing to support the PAC-3 MSE’s integration into naval vessels, this might no longer be the case moving forward.
As Congress works towards passing the National Defense Authorization Act (NDAA), three out of the four Congressional Defense Committees indicated their support for the integration of PAC-3 MSE interceptors on the Navy’s surface vessels.
The House Armed Service Committee (HASC), in their version of the FY25 defense bill added language which calls for the Secretary of the Navy to brief lawmakers on the progress of integrating the PAC-3 MSE on surface vessels.
Furthermore the briefings will include details on the Navy’s plans to accelerate flight testing of the missile presumably from naval vessels.
The Senate Armed Service Committee (SASC) in their bill allocated $30M towards the effort to integrate PAC-3 MSE into Aegis, while the Senate Appropriations Committee (SAC) bill recommended $75M in emergency funding for integrating PAC-3 MSE with the Aegis Combat System.