The US Army has begun fielding its new Sentinel A4 radar, a next-generation sensor that is already arriving in units while a much larger wave of systems is queued up behind it. The first deliveries from the second low-rate production lot mark a shift from development to operational use, even as testing and procurement decisions continue in parallel. For a service racing to keep pace with drones, cruise missiles, and other low-flying threats, the Sentinel A4 is moving from PowerPoint to the battlefield at a notable clip.
At its core, the program is about replacing aging Sentinel A3 radars with a more capable design that can see farther, react faster, and plug into modern air and missile defense networks. The early fielding of these trailer-mounted systems is already shaping how the Army plans to defend critical sites, from the National Capital Region to forward bases, while setting the stage for full-rate production decisions that will determine how many radars ultimately join the force.
From prototype to production: a milestone delivery
The clearest sign that the Sentinel A4 is no longer just a test article is the arrival of the first radar from the program’s second low-rate initial production lot, known as LRIP 2. The US Army received the first of 19 Sentinel A4 radars built under LRIP 2, a handover that moves the system closer to routine fielding across air defense units. That delivery, highlighted in Army-focused reporting and by By Colton Jones, underscores how the service is now transitioning from engineering work to operational integration of the Sentinel.
Lockheed Martin has framed this as a major step for its Radar and Sensor Systems business, with the company emphasizing that the Sentinel A4 is a next-generation 360-degree radar designed to support integrated air and missile defense missions. In official Sentinel A4 updates, the manufacturer notes that the system is intended to detect and track a wide range of aerial threats, from small unmanned aircraft to helicopters and fixed-wing aircraft, while fitting into the Army’s broader modernization push. For a program that has been in development for years, the LRIP 2 delivery is the moment when the radar starts to become a real tool for commanders rather than a lab project.
What the Sentinel A4 brings to the fight
Technically, the Sentinel A4 is more than a simple upgrade of the older A3 variant; it is a substantial redesign aimed at modern threats. The radar’s 360-degree coverage is central to that shift, giving air defense units persistent awareness in all directions instead of relying on narrower fields of view. According to program descriptions, the system is built to offer improved sensitivity, coverage, and reliability compared with the Sentinel A3, which is critical as adversaries lean on low-flying cruise missiles and small drones that are easy to miss.
Lockheed Martin has highlighted that the Sentinel A4 is meant to operate as part of integrated air and missile defense architectures, not as a standalone sensor. In its own Next-generation messaging, the company stresses that the radar is optimized to cue interceptors and command systems against threats that include rockets, artillery, and mortars, as well as helicopters and fixed-wing aircraft. A separate breakdown of What Was Delivered reinforces that the Army sees the Sentinel A4 as a core sensor for short-range air defense units that must now contend with swarming drones and precision-guided munitions in contested airspace.
Fielding plans: from the capital to the wider force
Even as the Army keeps some unit assignments under wraps, there are clear indications of where the Sentinel A4 will first stand guard. Earlier reporting has pointed to the National Capital Region as the site of the radar’s first full operational deployment, with a trailer-mounted Sentinel A4 expected to help defend the Nation’s Capital as the system matures. That plan reflects a familiar pattern in US air defense, where the most sensitive locations, including the Capital, often receive new capabilities before they spread to the rest of the force.
While neither the service nor Lockheed has publicly detailed every unit that will receive the initial radars, coverage citing Army planning suggests that air defense formations responsible for high-priority sites are at the front of the line. Additional reporting notes that While specific units have not been named, the early LRIP 2 deliveries are intended to support both operational use and continued testing. That dual role is typical for new radars, which must prove themselves in real-world conditions even as engineers refine software and tactics.
Industrial base, contracts, and the road to full-rate production
Behind the fielding story sits a substantial industrial and contracting effort centered on Lockheed Martin facilities in New York. Lockheed Martin Corp., Liverpool, New York, has been awarded a contract valued at $281,076,4xx for Sentinel A4 production, a figure that reflects the Army Orders 18 Sentinel A4 Radar Systems Through 2026. That award, tied to the designation Radar Systems Through 2026, underscores how the service is locking in near-term buys even before a final full-rate production decision is made.
Corporate statements from SYRACUSE, N.Y., describe how Lockheed Martin has delivered the first Sentinel A4 radar from Low-Rate Initial Production 2 and is advancing toward full-rate production, with the company trading under the ticker NYSE: LMT. A separate contracting summary notes that Lockheed Martin Corp in Liverpool, New York, is responsible for building the 18 systems covered by the current order, which will run through 2026. These moves, combined with the LRIP 2 deliveries, show an industrial base that is already scaling up even as the Army keeps some options open.
Testing, delays, and what comes next
For all the momentum, the Sentinel A4 program is not simply racing unchecked into mass production. The Army had originally planned to make a full-rate production decision on Lockheed’s Sentinel A4 in October, but The Army pushed that timeline into 2026 to conduct more intense combat testing. That delay reflects a broader trend in Pentagon acquisition, where services are increasingly willing to slow procurement decisions to gather more operational data, particularly for systems that will anchor critical missions like short-range air defense.
At the same time, the Army is already treating the Sentinel A4 as a major milestone for air and missile defense. A video message from Army partners described the first Sentinel A4 radar from the program’s second low-rate initial production lot as a major milestone for Army air and missile defense, highlighting how the system is expected to strengthen integrated defenses once full rate production is authorized. Additional coverage notes that The US Army received its first of 19 Sentinel A4 radars as part of low-rate initial production 2 from Lockheed Martin, with The Sentinel described as a key step on the path to full-rate production. A separate technical summary explains that Sentinel A4 is slated to replace the Army’s currently fielded Sentinel A3 radars, and that during the initial test and evaluation phase the system must prove its performance before full rate production is authorized.
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