Background

In March 2020, the U.S. Marine Corps (USMC) announced a major force design initiative planned to occur over 10 years originally referred to as "Force Design 2030" which is now known as "Force Design." Under Force Design, the Marines are redesigning forces to place a stronger emphasis on naval expeditionary warfare. As part of the redesign, the Marines plan to establish at least three Marine Littoral Regiments (MLRs) organized, trained, and equipped to accomplish a number of missions within contested maritime spaces.

MLR Missions

According to the Marines, the MLR is to be capable of the following missions:

Conduct Expeditionary Advanced Base Operations (EABO), a form of expeditionary warfare involving the employment of naval expeditionary forces. Selected Marine and Navy forces are to be arrayed in a series of austere, temporary locations ashore within a contested or potentially contested maritime area to conduct sea denial and control and fleet sustainment operations.
Conduct strike operations with a variety of systems.
Coordinate air and missile defense operations.
Support maritime domain awareness.
Support naval surface warfare operations.
Support information operations.

The MLR's Operational Environment

The Commandant of the Marine Corps' May 2022 Force Design 2030 Annual Update stated

The security environment is characterized by proliferation of sophisticated sensors and precision weapons coupled with growing strategic competition. Potential adversaries employ systems and tactics to hold the fleet and Joint Force at arm's length, allowing them to employ a strategy that uses contested areas as a shield behind which they can apply a range of coercive measures against our allies and partners.

Operating in this environment, MLRs are intended to serve as what the Marines call a "Stand-In Force (SIF)," designed to help the fleet and joint force win the reconnaissance and counter reconnaissance battle within a contested area at the leading edge of a maritime defense-in-depth.

MLR Employment

According to a May 25, 2022, Marine Corps Association article "Missions, MAGTFs, Force Design & Change," by Colonel Michael R. Kennedy, USMC (Retired), MLRs are intended to

Deploy to islands, coastlines, and observation posts along chokepoints where their networked sensors and weapons can surveil the air and surface (and, potentially subsurface) waterways. The MLR's purpose will be to observe and prevent any "grey zone" activities that lead to fait accompli actions.

MLR Organizational Structure

Figure 1. Generic MLR

Source: Marine Corps Information Paper provided to CRS, April 3, 2025

Notes: H&S = Headquarters and Services; GBAB = Ground Based Air Defense

As currently envisioned, the MLR is to consist of approximately 1,800 to 2,000 Sailors and Marines composed of four elements:

Command Element. A regimental headquarters with enhanced signals and human intelligence, reconnaissance, communications, logistics planning, civil affairs, cyber, and information operations capabilities.
Littoral Combat Team consisting of an infantry battalion and an anti-ship missile battery. The Littoral Combat Team is to provide the basis for multiple reinforced platoon-sized expeditionary advanced base sites capable of conducting a variety of missions.
Littoral Anti-Air Battalion designed to conduct air defense, air surveillance and early warning, air control, and forward rearming and refueling operations.
Littoral Logistics Battalion designed to resupply expeditionary advanced base sites, manage cache sites, and connect with higher-level logistics providers. The Littoral Logistics Battalion is also to provide limited purchasing authority, medical support, ammunition and fuel distribution, and field maintenance.

Selected MLR Systems

In order to accomplish the wide range of MLR missions, the Marines and Navy are pursuing a number of essential systems including, but not limited to, the following:

Navy-Marine Corps Expeditionary Ship Interdiction System (NMESIS)

NMESIS consists of the Naval Strike Missile mounted on the Joint Light Tactical Vehicle (JLTV). Reportedly, NMESIS batteries will be composed of 18 launchers, separated into two platoons of nine launchers each. The Marines plan to field 14 batteries, three of which are planned to be deployed to MLRs, while 11 will be used to support of rotational Marine Expeditionary Unit (MEU) deployments. Reportedly, the 3^rd MLR received its NMESIS fire units in late November 2024, which are to be assigned to the 3^rd MLR's Medium-Range Missile Battery stationed in Oahu, HI.

NMESIS Deployed to Luzon for Balikitan 2025

Reportedly, the 3^rd MLR's NMESIS battery is to be deployed to the Luzon Straights during Exercise Balikitan 2025, scheduled to take place in April and May 2025. It was further noted that

the Luzon Strait sits between Taiwan and the Philippines and is roughly 220 miles across at its narrowest point. It is a critical shipping artery and also an incredibly important military conduit.

With NMESIS deployed to the Luzon Straights reportedly

[it] would be able to put any vessel transiting the waterway from the tip of Taiwan, nearly to the northern reaches of Luzon in the Philippines, and 100 miles east to west, at risk.

Marine Air Defense Integrated System (MADIS)

According to the Marines,

MADIS is a short-range, surface-to-air system that enables [MLR] Low Altitude Air Defense Battalions to deter and neutralize unmanned aircraft systems and fixed wing/rotary wing aircraft. Mounted aboard two JLTVs, MADIS has an organic radar and tracking system, a 30 mm cannon, and Stinger anti-aircraft missiles.

Reportedly, on December 13, 2024, MADIS was fielded to the 3^rd Littoral Anti-Air Battalion in Hawaii. More MADIS systems are planned to be fielded in the fourth quarter of FY2025. The Marines plan to deploy the 3^rd MLR's MADIS systems to Balikitan 2025 to conduct live fire training with the Philippine military.

Ground/Air Task Oriented Radar (G/ATOR)

According to the Marines

G/ATOR is a three-dimensional, expeditionary, short/medium-range multirole radar capable of detecting low-observable, low-radar-cross-section targets such as rockets, artillery, mortars, cruise missiles, and manned and unmanned aerial systems.

MLR Establishment

On March 3, 2022, the Marines redesignated the 3^rd Marine Regiment as the 3^rd MLR at Marine Corps Base Hawaii. The 3^rd MLR is expected to achieve FOC in FY2025. Reportedly, the 12^th Marine Artillery Regiment stationed in Okinawa is to be reorganized into the 12^th MLR by 2025. On December 5, 2024, the 12^th Littoral Anti-Air Battalion was activated at Camp Hansen Okinawa, Japan. Reportedly, on January 10, 2025, the 1^st Battalion, 4^th Marines held a redesignation ceremony at Camp Pendleton, California, and are to be incorporated into the 12^th MLR, which is to be part of the 3^rd Marine Division, III Marine Expeditionary Force. The Marines also reportedly plan to transfer the 4^th Marine Regiment from Okinawa to Guam, where it is scheduled to be reorganized into the 4^th MLR in 2027. Reportedly, this Guam-based MLR is to rely on rotational forces as opposed to permanently stationed Marines.

Potential Issues for Congress

Potential issues for Congress could include the following:

MLR Utility Outside the Indo-Pacific

While Marine leadership have noted MLRs are being designed to operate in the Indo-Pacific region, the Marines have global security responsibilities. Russia's February 2022 invasion of Ukraine has arguably changed the global security environment and raises potential questions about what role MLRs might play outside of the Indo-Pacific region. If three Indo-Pacific MLRs are needed to support operations in the region, are there plans to develop MLRs for other regions? Congress might decide to examine MLR structure and capabilities in regards to how MLRs might support potential NATO operations and if additional MLRs should be created to support operations outside the Indo-Pacific region.

Role of the Navy Medium Landing Ship (LSM)

The Marines have noted Stand-In Forces require organic operational mobility, such as the LSM, to deploy and sustain MLRs. The Navy envisions procuring up to 35 LSMs and had planned procuring the first LSM in FY2023, but deferred the procurement of the first LSM to FY2025. With the Navy's reported December 2024 cancellation of the LSM request for proposal, the future of the LSM program could be in doubt. Given the Marines' requirement for LSMs to support operational requirements in the Indo-Pacific region and the possibility that acquisition of LSMs could be significantly delayed or postponed altogether, Congress might examine the feasibility of the Marines' Indo-Pacific strategy if LSM procurement is delayed, postponed, or if fewer LSMs are procured due to cost limitations. If Congress deems the Marines' Indo-Pacific strategy too risky without the required LSMs, Congress might decide to reprioritize Navy shipbuilding plans or provide additional funding for the LSM program.

Additional Reading

CRS Report R47614, U.S. Marine Corps Force Design Initiative: Background and Issues for Congress, by Andrew Feickert