Air Defense

Sentinel A4

Also known as
  • AN/MPQ-64A4
  • AN/MPQ-64A4 Sentinel A4
  • Sentinel A4 radar

Lockheed Martin's AN/MPQ-64A4 Sentinel A4 is a U.S. Army trailer-mounted air and missile defense radar replacing the Sentinel A3. The digital X-band AESA sensor is built to detect cruise missiles, UAS, fixed-wing and rotary-wing aircraft, and rocket, artillery, and mortar threats while feeding Army and integrated air-defense command networks.

Sentinel A4, Air and missile defense radar, Air Defense
Image source: Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 1 of 6]
Profile / Specs

Profile

Origin
United States
Type
Air and missile defense radar
Service note
2020s-present
Designed
2019
Produced
2023-present
Developed from
AN/MPQ-64A3 Sentinel A3

Specifications

Radar band
X-band
Architecture
Digital active electronically scanned array (AESA)
Coverage
360-degree hemispheric surveillance and fire control
Threats
Cruise missiles, UAS, fixed-wing and rotary-wing aircraft, rockets, artillery, and mortars
Command-and-control links
Designed to feed Army IBCS, FAAD-C2, IFPC, and other integrated air-defense networks
Mobility
Mounted on a modified M1095 trailer with generator and communications equipment on an M1083 FMTV cargo truck
Acquisition objective
240 radars
Compatible Air Defense Systems

Sentinel A4 is a sensor rather than a shooter; the sources frame it as a radar feeding command-and-control networks and layered air-defense systems.

Compatible itemItem typeCompatibility evidence
NASAMS, Medium-range surface-to-air missile system, Air DefenseNASAMSNetworked surface-to-air missile system

Lockheed Martin lists NASAMS among the defense systems Sentinel A4 can integrate with, alongside IFPC, NCR-IADS, Aegis Combat Management System, and NORAD examples.

Sources: Sentinel A4 | Lockheed Martin

Air Defense Network Role

Sentinel A4's importance is its sensor role inside layered air defense. It supplies radar tracks and fire-control-quality data to command systems and shooters rather than intercepting threats itself.

LayerSource-backed roleWhy it matters
SensorThree-dimensional X-band AESA radar for low- to mid-altitude air threats and RAM detection.Replaces the Sentinel A3 with a multi-mission radar able to search, track, classify, identify, and report more varied threats.
Command networkDesigned to integrate with Army IBCS and FAAD-C2 while providing data to command-and-control systems.Lets air-defense units pass track data into a wider engagement network instead of treating the radar as an isolated sensor.
IFPCDOT&E describes Sentinel as the primary fire-control radar for IFPC Inc 2, with A4 intended to replace A3 before IFPC IOT&E.Connects Sentinel A4 to the Army's fixed and semi-fixed site defense layer against drones, cruise missiles, and RAM threats.
Early fieldingLockheed Martin reported LRIP 2 delivery and IOT&E Phase I completion in February 2026; DVIDS later documented Eighth Army training in South Korea.Shows the radar moving from program testing into unit training and fielding activity without claiming confirmed combat use.
Timeline

Sentinel A4 Key Events

  1. Army awards the Sentinel A4 development contract

    Lockheed Martin announced that the U.S. Army had awarded the company a contract to develop the Sentinel A4 radar.

    Sources: U.S. Army Awards Lockheed Martin Contract to Develop Sentinel A4 Radar

  2. First radar completed

    Lockheed Martin reported that the first Sentinel A4 radar was completed in August 2022.

    Sources: Sentinel A4 | Lockheed Martin - First radar completed

  3. Limited user testing begins at White Sands

    U.S. Army Operational Test Command described a three-week limited user test using a section-sized Sentinel A4 element in integrated fire protection, short-range air defense, and counter-RAM mission scenarios.

    Sources: Modernized Sentinel sensor test eyes growing threat variety

  4. Army approves low-rate initial production

    Defense News reported Army approval for low-rate initial production, with 19 systems scheduled for delivery by fiscal 2025 and an acquisition objective of 240 radars.

    Sources: US Army approves Sentinel A4 air defense radar for low-rate production

  5. First LRIP 2 radar delivered

    Lockheed Martin said it delivered the first Sentinel A4 radar from Low-Rate Initial Production 2 to the U.S. Army and completed the first phase of initial operational test and evaluation.

    Sources: Lockheed Martin Delivers First Sentinel A4 from LRIP 2, Advances Toward Full-Rate Production

  6. Eighth Army trains with Sentinel A4 in South Korea

    DVIDS documented U.S. Army soldiers from the 35th Air Defense Artillery Brigade training on the newly implemented Sentinel A4 radar at Camp Humphreys.

    Sources: Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Video]

Media

Sentinel A4 Videos

Sentinel A4 Images

Sentinel A4, Air and missile defense radar, Air Defense - view 1
Source: Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 1 of 6]
Sentinel A4, Air and missile defense radar, Air Defense - view 2
Source: Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 1 of 6]
Sentinel A4, Air and missile defense radar, Air Defense - view 3
Source: Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 1 of 6]
Related Weapon Systems
AN/MPQ-64 Sentinel, Mobile 3D air-defense radar, Air DefenseAir DefenseAN/MPQ-64 SentinelMobile 3D air-defense radarThe AN/MPQ-64 Sentinel is a Raytheon mobile X-band 3D air-defense radar used to cue short-range air-defense weapons, NASAMS batteries, and newer IFPC launchers against aircraft, helicopters, drones, cruise missiles, and other low-altitude threats. U.S. records identify Sentinel transfers and training for Ukraine in 2022, a DSCA notice later named the MPQ-64F1 in Ukraine's NASAMS package, and follow-on reporting documents sustainment and visual-loss evidence.
AN/TPQ-53 multimission radar, Mobile multimission counterfire and air-surveillance radar, Electronic WarfareElectronic WarfareAN/TPQ-53 multimission radarMobile multimission counterfire and air-surveillance radarThe AN/TPQ-53, commonly called Q-53, is a Lockheed Martin mobile active electronically scanned array radar that began as the Army's counterfire replacement for AN/TPQ-36 and AN/TPQ-37 Firefinder radars. Its baseline mission is to detect, classify, track, and locate mortar, artillery, and rocket launches in 90-degree or 360-degree modes, while software and open-architecture upgrades have extended the same family into counter-UAS, air-surveillance, and wider multimission radar roles.
EL/M-2084 Multi-Mission Radar, Mobile multi-mission air-defense and weapon-locating radar, Air DefenseAir DefenseEL/M-2084 Multi-Mission RadarMobile multi-mission air-defense and weapon-locating radarThe EL/M-2084 Multi-Mission Radar is IAI/ELTA's mobile AESA radar family for air surveillance, counter-rocket/artillery/mortar warning, weapon locating, and air-defense fire-control support. Public IAI reporting identifies MMR as a sensor tied to Iron Dome, David's Sling, Barak MX, and Spyder architectures, while official Canadian, Czech, and Slovak sources show the radar family also serving NATO air-surveillance and ground-force sensor roles. IAI directly names Multi-Mission Radar systems in Israel's Operation Rising Lion defense against Iranian rockets, missiles, UAVs, and other airborne threats.

Sources

Sentinel A4 | Lockheed MartinPublisher: Lockheed Martin | Note: Supports Sentinel A4 manufacturer background, replacement of Sentinel A3, mission role, integrated air-defense compatibility, mobility, and general specifications. | Accessed: 2026-07-01Sentinel A4 Product CardPublisher: Lockheed Martin | Note: Supports Sentinel A4 2025 initial fielding language, production context, and core program specifications. | Accessed: 2026-07-01DOT&E FY2024 Annual Report - Army - Sentinel A4 RadarPublisher: Director, Operational Test & Evaluation | Note: Supports Sentinel A4 radar role as a three-dimensional X-band phased array system, its counter-RAM mission, and its use in Army integrated air and missile defense. | Accessed: 2026-07-01DOT&E FY2025 Annual Report - Army - IFPC Inc 2Publisher: Director, Operational Test & Evaluation | Note: Supports Sentinel's primary fire-control radar role in IFPC Inc 2 and the planned replacement of Sentinel A3 by Sentinel A4 before IFPC IOT&E. | Accessed: 2026-07-01Modernized Sentinel sensor test eyes growing threat varietyPublisher: U.S. Army | Note: Supports the April 2023 limited user test, IBCS integration context, section-sized test configuration, and operationally realistic mission scenarios. | Accessed: 2026-07-01US Army approves Sentinel A4 air defense radar for low-rate productionPublisher: Defense News | Note: Supports Sentinel A4 low-rate initial production approval, scheduled early deliveries, and the Army acquisition objective of 240 systems. | Accessed: 2026-07-01U.S. Army Awards Lockheed Martin Contract to Develop Sentinel A4 RadarPublisher: PR Newswire / Lockheed Martin | Note: Supports the 2019 Sentinel A4 development contract award and program launch. | Accessed: 2026-07-01Sentinel A4 | Lockheed Martin - First radar completedPublisher: Lockheed Martin | Note: Supports the September 2022 Sentinel A4 progress milestone noted on Lockheed Martin's product page. | Accessed: 2026-07-01Lockheed Martin Delivers First Sentinel A4 from LRIP 2, Advances Toward Full-Rate ProductionPublisher: Lockheed Martin | Note: Supports the February 2026 LRIP 2 delivery milestone, IOT&E Phase I completion, FAAD-C2 integration, and production status. | Accessed: 2026-07-01Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Video]Publisher: Defense Visual Information Distribution Service | Note: Supports the April 2026 Eighth Army training context at Camp Humphreys and documents the radar in U.S. Army training use. | Accessed: 2026-07-01Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 1 of 6]Publisher: Defense Visual Information Distribution Service | Note: Supports public-domain image provenance for the primary Sentinel A4 gallery image. | Accessed: 2026-07-01Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 2 of 6]Publisher: Defense Visual Information Distribution Service | Note: Supports public-domain image provenance for a second Sentinel A4 gallery image. | Accessed: 2026-07-01Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 3 of 6]Publisher: Defense Visual Information Distribution Service | Note: Supports public-domain image provenance for a third Sentinel A4 gallery image. | Accessed: 2026-07-01Eighth Army Showcases New Sentinel A4 Radar During Training at Camp Humphreys [Image 4 of 6]Publisher: Defense Visual Information Distribution Service | Note: Supports public-domain image provenance for a fourth Sentinel A4 gallery image. | Accessed: 2026-07-01