The MIM-104 Patriot is a mobile interceptor missile surface-to-air missile (SAM) system, the primary such system used by the United States Army and several allied states. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar component of the weapon system. The AN/MPQ-53 at the heart of the system is known as the "Phased Array Tracking Radar to Intercept on Target", which is a backronym for "Patriot". In 1984, the Patriot system began to replace the Nike Hercules system as the U.S. Army's primary high to medium air defense (HIMAD) system and the MIM-23 Hawk system as the U.S. Army's medium tactical air defense system. In addition to defending against aircraft, Patriot is the U.S. Army's primary terminal-phase anti-ballistic missile (ABM) system. As of 2016, the system is expected to stay fielded until at least 2040. Patriot uses an advanced aerial interceptor missile and high-performance radar systems. Patriot was developed at Redstone Arsenal in Huntsville, Alabama, which had previously developed the Safeguard ABM system and its component Spartan and hypersonic Sprint missiles. The symbol for Patriot is a drawing of a Revolutionary War–era minuteman. The MIM-104 Patriot has been widely exported. Patriot was one of the first tactical systems in the U.S. Department of Defense (DoD) to employ lethal autonomy in combat. The system was deployed in the 1991 Gulf War, and made successful intercepts in the 2003 Iraq War. In August 2014 batteries first downed UAVs when Israeli Air Defense Command engaged two Hamas drones during the 2014 Gaza War. Patriot systems have been used since 2015 by the Saudi and Emirati air forces in the Yemeni Civil War, against Houthi missiles. Since 2023, Ukraine has operated Patriot systems in the Russo-Ukrainian War, downing Russian Su-34 and Su-35 fighters, Mi-8 helicopters, and Kinzhal ballistic missiles.
== Introduction == Prior to the Patriot, Raytheon was involved in a number of surface to air missile programs, including FABMDS (Field Army Ballistic Missile Defense System), AADS-70 (Army Air-Defense System – 1970) and SAM-D (Surface-to-Air Missile – Development). In 1975, the SAM-D missile successfully engaged a drone at the White Sands Missile Range. In 1976, it was renamed the PATRIOT Air Defense Missile System. The MIM-104 (Mobile Interceptor Missile 104) Patriot combined several new technologies, including the MPQ-53 passive electronically scanned array radar and track-via-missile guidance. Full-scale development of the system began in 1976 and it was deployed in 1984. Patriot was used initially as an anti-aircraft system. In 1988, it received an upgrade providing limited capability against tactical ballistic missiles (TBM), designated PAC-1 (Patriot Advanced Capability 1). The most recent upgrade by manufacturer Lockheed Martin, designated PAC-3, is a nearly total system redesign of the interceptor missiles, this time designed from the outset with the capability to engage and destroy tactical ballistic missiles. The Army plans to upgrade the Patriot system as part of the Integrated Air and Missile Defense system designed to tie into a broader air defense architecture using an Integrated Battle Command System (IBCS).
Patriot equipment
The Patriot system has four major operational functions: communications, command and control, radar surveillance, and missile guidance. The four functions combine to provide a coordinated, secure, integrated, mobile air defense system. The Patriot system is modular and highly mobile. A battery-sized element can be installed in less than an hour. All components, consisting of the fire control section (radar set, engagement control station, antenna mast group, electric power plant) and launchers, are truck- or trailer-mounted. The radar set and launchers with missiles are mounted on M860 semi-trailers, which are towed by Oshkosh M983 HEMTTs.
Missile reloading is accomplished using a M985 HEMTT truck with a Hiab crane on the back. This crane is larger than the standard Grove cranes found on regular M977 HEMTT and M985 HEMTT cargo body trucks. The crane truck, known as a Guided Missile Transporter (GMT), removes spent missile canisters from the launcher and replaces them with fresh missiles. Because the crane nearly doubles the height of the HEMTT when not stowed, crews informally refer to it as the "scorpion tail". A standard M977 HEMTT with a regular-sized crane is sometimes referred to as the Large Repair Parts Transporter (LRPT). The heart of the Patriot battery is the fire control section, consisting of the AN/MPQ-53 or −65/65A Radar Set (RS), the AN/MSQ-104 or −132 Engagement Control Station (ECS), the OE-349 Antenna Mast Group (AMG), and the EPP-III Electric Power Plant (EPP). The system's missiles are transported on and launched from either the M901 Launching Station (LS), which can carry up to four PAC-2 missiles; the M902 LS, with sixteen PAC-3 missiles; or the M903 LS, which can be configured to carry PAC-2, PAC-3, and MSE/SkyCeptor missiles in various combinations. A Patriot battalion is also equipped with the Information Coordination Central (ICC), a command station designed to coordinate the launches of a battalion and uplink Patriot to the JTIDS or MIDS network.
==== AN/MPQ-53, -65 and -65A Radar Set ==== The AN/MPQ-53/65 Radar Set is a passive electronically scanned array radar equipped with IFF, electronic counter-countermeasure (ECCM), and track-via-missile (TVM) guidance subsystems. The AN/MPQ-53 Radar Set supports PAC-2 units, while the AN/MPQ-65 Radar Set supports PAC-2 and PAC-3 units. The main difference between these two radars is the addition of a second travelling-wave tube (TWT), which gives the −65 radar increased search, detection, and tracking capability. The radar antenna array consists of over 5,000 elements that "deflect" the radar beam many times per second. The radar antenna array contains an IFF interrogator subsystem, a TVM array, and at least one "sidelobe canceller" (SLC), which is a small array designed to decrease interference that might affect the radar. Patriot's radar is somewhat unusual in that it is a "detection-to-kill" system, meaning that a single unit performs all search, identification, track, and engagement functions. Most other SAM systems, by contrast, require several different radars to perform all functions necessary to detect and engage targets.
The beam created by the Patriot's flat phased array radar is comparatively narrow and highly agile compared to that of a moving dish. This characteristic gives the radar the ability to detect small, fast targets like ballistic missiles, or low radar cross-section targets such as stealth aircraft or cruise missiles. The power and agility of Patriot's radar is also highly resistant to countermeasures, including ECM, radar jamming, and use of RWR equipment. Patriot is capable of quickly changing frequencies to resist jamming. However, the radar can suffer from "blind spots".
The Army is planning upgrades to the Patriot system's radar components, including a new digital processor that replaces the one used since the system's introduction. In 2017, the Patriot got a new AN/MPQ-65A active electronically scanned array (AESA) radar that has greater range and sharper discrimination. The main gallium nitride (GaN)-based AESA array measures 9 ft × 13 ft (2.7 m × 4.0 m), is a bolt-on replacement for the current antenna, and is oriented toward the primary threat; two new rear panel arrays are a quarter the size of the main array and let the system look behind and to the sides, providing 360-degree coverage. The GaN AESA radar also has up to 50 percent less maintenance costs. Instead of shining a single transmitter through many lenses, the GaN array uses many smaller transmitters, each with its own control, increasing flexibility and allowing it to work even if some transmitters do not. In October 2017, the Army announced Raytheon's Lower-Tier Air and Missile Defense System (LTAMDS) radar had been selected as the Patriot system's new radar. Unlike the previous radar which could only watch one part of the sky at a time primarily to detect ballistic missiles, the LTAMDS has 360-degree coverage to detect low flying and maneuvering drones and cruise missiles. The design has one large main array flanked by two smaller arrays, with the main panel still focused on high-altitude threats and the side panels, which are half the size with twice the power of the previous radar set, able to detect slower threats from considerable distance. Raytheon was awarded a US$383 million contract to build the first six radars to enter service in 2022.
AN/MSQ-104 and -132 Engagement Control Station
The AN/MSQ-104 or AN/MSQ-132 Engagement Control Station (ECS) is the nerve center of the Patriot firing battery, costing approximately US$6 million per unit. The ECS consists of a shelter mounted on the bed of an M927 5-Ton Cargo Truck or on the bed of a Light Medium Tactical Vehicle (LMTV) cargo truck. The main subcomponents of the ECS are the Weapons Control Computer (WCC), the Data Link Terminal (DLT), the UHF communications array, the Routing Logic Radio Interface Unit (RLRIU), and the two-person stations that serve as the system's human machine interface. The ECS is air conditioned, pressurized (to resist chemical/biological attack), and shielded against electromagnetic pulse (EMP) or other such electromagnetic interference. The ECS also contains several SINCGARS radios to facilitate voice communications. The WCC is the main computer within the Patriot system. This computer controls the operator interface, calculates missile intercept algorithms, and provides limited fault diagnostics. It was designed as a 24-bit parallel militarized computer with fixed- and floating-point capability, organized in a multiprocessor configuration that operates at a maximum clock rate of 6 MHz. Compared to modern personal computers, this represents very limited processing power, so the computer has been upgraded several times during Patriot's service life. The latest variant fielded in 2013 has performance improved by several orders of magnitude. The DLT connects the ECS to Patriot's Launching Stations. It uses either a SINCGARS radio or fiber optic cables to transmit encrypted data between the ECS and the launchers. Through the DLT, the system operators can remotely emplace, slew or stow launchers, perform diagnostics on launchers or missiles, and fire missiles. The UHF communications array consists of three UHF radio "stacks" and their associated patching and encrypting equipment. These radios are connected to the antennas of the OE-349 Antenna Mast Group, which are used to create UHF "shots" between sister Patriot batteries and their associated ICC. This creates a secure, real-time data network (known as PADIL, Patriot Data Information Link) that allows the ICC to centralize control of its subordinate firing batteries. The RLRIU functions as the primary router for all data coming into the ECS. The RLRIU gives a firing battery an address on the battalion data network, and sends/receives data from across the battalion. It also "translates" data coming from the WCC to the DLT, facilitating communication with the launchers. Patriot's crew stations are referred to as Manstation 1 and 3 (MS1 and MS3). These are the stations where Patriot operators interface with the system. The manstations consist of a monochrome (green and black) screen surrounded by various Switch Indicators. Each manstation also has a traditional QWERTY keyboard and isometric stick, a tiny joystick that functions much like a PC mouse. It is through these switch indicators and the Patriot user interface software that the system is operated. With newer upgrades, the operator's monochrome screen and physical switches have been replaced with two 30 in (760 mm) touchscreen LCDs and a standard keyboard/mouse at both stations.
OE-349 Antenna Mast Group
The OE-349 Antenna Mast Group (AMG) is mounted on an M927 5-Ton Cargo Truck. It includes four 4 kW antennas in two pairs on remotely controlled masts. Emplacement of the AMG can have no greater than a 0.5-degree roll and a 10-degree crossroll. The antennas can be controlled in azimuth, and the masts can be elevated up to 100 feet 11 inches (30.76 m) above ground level. Mounted at the base of each pair of antennas are two high-power amplifiers associated with the antennas and the radios in the co-located shelter. It is through these antennas that the ECS and ICC send their respective UHF "shots" to create the PADIL network. The polarity of each shot can be changed by adjusting the "feedhorn" to a vertical or horizontal position. This enables a greater chance of communication shots reaching their intended target when terrain obstacles may otherwise obscure the signal.
EPP-III Electric Power Plant
The EPP-III Diesel-Electric Power Plant (EPP) is the power source for the ECS and Radar. The EPP consists of two 150 kilowatt diesel engines with 400 hertz, 3-phase generators that are interconnected through the power distribution unit. The generators are mounted on a trailer or modified M977 HEMTT. Each EPP has two 100-US-gallon (380 L) fuel tanks and a fuel distribution assembly with grounding equipment. Each diesel engine can operate for more than eight hours with a full fuel tank. The EPP delivers its power to the Radar and ECS through cables stored in reels alongside the generators. It powers the AMG via a cable routed through the ECS.
M901/902/903 Launching Station
The M90x Launching Stations are remotely operated, self-contained units. The ECS controls operation of the launchers through each launcher's DLT, via fiber optic or VHF (SINCGARS) data link. Integral levelling equipment permits emplacement on slopes of up to 10 degrees. Each launcher is trainable in azimuth and elevates to a fixed, elevated launch position. Precise aiming of the launcher before launch is not necessary; thus, no extra lags are introduced into system reaction time. Each launcher is capable of providing detailed diagnostics to the ECS via the data link. The launching station contains four major equipment subsystems: the launcher generator set, the launcher electronics module (LEM), the launcher mechanics assembly (LMA), and the launcher interconnection group (LIG). The generator set consists of a 15 kW, 400 Hz generator that powers the launcher. The LEM is used for the real-time implementation of launcher operations requested via data link from the ECS. The LMA physically erects and rotates the launcher's platform and its missiles. The LIG connects the missiles themselves to the launcher via the Launcher Missile Round Distributor (LMRD).
Patriot guided missile
The first fielded variant was the MIM-104A "Standard". It was optimized solely for engagements against aircraft and had very limited capability against ballistic missiles. It had a range of 70 km (43 mi), and a speed in excess of Mach 2. The MIM-104B "anti-standoff jammer" (ASOJ) is a missile designed to seek out and destroy ECM emitters. The MIM-104C PAC-2 missile was the first Patriot missile that was optimized for ballistic missile engagements. The GEM series of missiles (MIM-104D/E) are further refinements of the PAC-2 missile. The PAC-3 missile is a new interceptor, featuring a Ka band active radar seeker, employing "hit-to-kill" interception, in contrast to previous interceptors' method of exploding in the vicinity of the target, destroying it with shrapnel, and several other enhancements which dramatically increase its lethality against ballistic missiles. The specific information for these different kinds of missiles are discussed in the "Variants" section. The first seven of these are in the larger PAC-2 configuration of a single missile per canister, of which four can be placed on a launcher. PAC-3 missile canisters contain four missiles, so that sixteen rounds can be placed on a launcher. The missile canister serves as both the shipping and storage container and the launch tube. Patriot missiles are referred to as "certified rounds" as they leave the factory, and additional maintenance is not necessary on the missile prior to it being launched. The PAC-2 missile is 5.8 metres (19 ft 0 in) long, weighs about 900 kilograms (2,000 lb), and is propelled by a solid-fueled rocket motor.
==== Patriot missile design ==== The PAC-2 family of missiles all have a fairly standard design, the only differences between the variants being certain internal components. They consist of (from front to rear) the radome, guidance section, warhead section, propulsion section, and control actuator section. The radome is made of slip cast fused silica approximately 16.5 millimetres (0.65 in) thick, with a nickel alloy tip, and a composite base attachment ring bonded to the slip cast fused silica and protected by a molded silicone rubber ring. The radome provides an aerodynamic shape for the missile and microwave window and thermal protection for the RF seeker and electronic components. The Patriot guidance section consists primarily of the modular digital airborne guidance system (MDAGS). The MDAGS consists of a modular midcourse package that performs all of the required guidance functions from launch through midcourse and a terminal guidance section. The TVM seeker is mounted on the guidance section, extending into the radome. The seeker consists of an antenna mounted on an inertial platform, antenna control electronics, a receiver, and a transmitter. The Modular Midcourse Package (MMP), which is located in the forward portion of the warhead section, consists of the navigational electronics and a missile-borne computer that computes the guidance and autopilot algorithms and provides steering commands according to a resident computer program. The warhead section, just aft of the guidance section, contains the proximity fuzed warhead, safety-and-arming device, fuzing circuits and antennas, link antenna switching circuits, auxiliary electronics, inertial sensor assembly, and signal data converter. The propulsion section consists of the rocket motor, external heat shield, and two external conduits. The rocket motor includes the case, nozzle assembly, propellant, liner and insulation, pyrogen igniter, and propulsion arming and firing unit. The casing of the motor is an integral structural element of the missile airframe. It contains a conventional, casebonded solid rocket propellant. The Control Actuator Section (CAS) is at the aft end of the missile. It receives commands from the missile autopilot and positions the fins. The missile fins steer and stabilize the missile in flight. A fin servo system positions the fins. The fin servo system consists of hydraulic actuators and valves and an electrohydraulic power supply. The electrohydraulic power consists of a battery, motor pump, oil reservoir, gas pressure bottle, and accumulator.
Variants
=== MIM-104A === Patriot was first introduced with a single missile type: the MIM-104A. This was the initial "Standard" missile, still known as "Standard" today. In Patriot's early days, the system was used exclusively as an anti-aircraft weapon, with no capability against ballistic missiles. This was remedied during the late 1980s when Patriot received its first major system overhaul with the introduction of the Patriot Advanced Capability missile and concurrent system upgrades.
=== MIM-104B (PAC-1) === Patriot Advanced Capability (PAC-1), known today as the PAC-1 upgrade, was a software-only upgrade. The most significant aspects of this upgrade were changing the way the radar searched and the way the system defended its assets. Instead of searching low to the horizon, the top of the radar's search angle was lifted to near vertical (89 degrees) from the previous angle of 25 degrees. This was done as a counter to the steep parabolic trajectory of inbound ballistic missiles. The search beams of the radar were tightened, and while in "TBM search mode" the "flash", or the speed at which these beams were shot out, was increased significantly. While this increased the radar's detection capability against the ballistic missile threat set, it decreased the system's effectiveness against traditional atmospheric targets, as it reduced the detection range of the radar as well as the number of "flashes" at the horizon. Because of this, it was necessary to retain the search functions for traditional atmospheric threats in a separate search program, which could be easily toggled by the operator based on the expected threat. The ballistic missile defense capability changed the way Patriot defended targets. Instead of being used as a system to defend a significant area against enemy air attack, it was now used to defend much smaller "point" targets, which needed to lie within the system's TBM "footprint". The footprint is the area on the ground that Patriot can defend against inbound ballistic missiles. In the 1980s, Patriot was upgraded in relatively minor ways, mostly via its software. The most significant of these was a special upgrade to discriminate and intercept artillery rockets in the vein of the multiple rocket launcher, which was seen as a significant threat from North Korea. This feature has not been used in combat and has since been deleted from U.S. Army Patriot systems, though it remains in South Korean systems. Another upgrade was the introduction of another missile type, designated MIM-104B and called "anti stand-off jammer" (ASOJ) by the Army. This variant is designed to help Patriot engage and destroy ECM aircraft at standoff ranges. It works similar to an anti-radiation missile in that it flies a highly lofted trajectory and then locates, homes in on, and destroys the most significant emitter in an area designated by the operator.
=== MIM-104C (PAC-2) === In the late 1980s, tests began to indicate that, although Patriot was certainly capable of intercepting inbound ballistic missiles, it was questionable whether the MIM-104A/B missile was capable of destroying them reliably. This necessitated the introduction of the PAC-2 missile and system upgrade. For the system, the PAC-2 upgrade was similar to the PAC-1 upgrade. Radar search algorithms were further optimized, and the beam protocol while in "TBM search" was further modified. PAC-2 saw Patriot's first major missile upgrade, with the introduction of the MIM-104C, or PAC-2 missile. This missile was optimized for ballistic missile engagements. Major changes to the PAC-2 missile were the size of the projectiles in its blast-fragmentation warhead, changed from around 2 grams to around 45 grams, and the timing of the pulse-Doppler radar fuze, which was optimized for high-speed engagements, though it retained its old algorithm for aircraft engagements if necessary. Engagement procedures were optimized, changing the method of fire the system used to engage ballistic missiles. Instead of launching two missiles in an almost simultaneous salvo, a brief delay between 3 and 4 seconds was added, in order to allow the second missile launched to discriminate a ballistic missile warhead in the aftermath of the explosion of the first. PAC-2 was first tested in 1987 and reached Army units in 1990, just in time for deployment to the Middle East for the Persian Gulf War. It was there that Patriot was first regarded as a successful ABM system and proof that ballistic missile defense was indeed possible. The complete study on its effectiveness remains classified. In April 2013, Raytheon received U.S. Army approval for a second recertification, extending the operational life of the worldwide inventory of Patriot missiles from 30 to 45 years.
=== MIM-104D (PAC-2/GEM) === There were more upgrades to PAC-2 systems throughout the 1990s and into the 21st century, mostly centering on software. The PAC-2 missiles were modified significantly—four separate variants became known collectively as guidance enhanced missiles (GEM). The main upgrade to the original GEM missile was a new, faster proximity fuzed warhead. Tests had indicated that the fuze on the original PAC-2 missiles were detonating their warheads too late when engaging ballistic missiles with an extremely steep ingress, and as such it was necessary to shorten this fuze delay. The GEM missile was given a new "low noise" seeker head designed to reduce interference in front of the missile's radar seeker, and a higher performance seeker designed to better detect low radar cross-section targets. The GEM was used extensively in Operation Iraqi Freedom (OIF), during which air defense was highly successful.
=== MIM-104E (PAC-2/GEM+) === Just prior to OIF, it was decided to further upgrade the GEM and PAC-2 missiles. This upgrade program produced missiles known as the GEM-T and the GEM-C, the "T" designator referring to tactical ballistic missiles, and the "C" designator referring to cruise missiles. These missiles were both given a totally new nose section, which was designed specifically to be more effective against low altitude, low RCS targets like cruise missiles. The GEM-T was given a new fuze which was further optimized against ballistic missiles and a new low noise oscillator which increases the seeker's sensitivity to low radar cross-section targets. The GEM-C is the upgraded version of the GEM, and the GEM-T is the upgraded version of the PAC-2. The GEM+ entered service in November 2002. In 2018, Raytheon upgraded the GEM-T guidance system with solid-state gallium nitride (GaN) transmitters. Domestic U.S. production of PAC-2 GEM-T missiles remains ongoing, with a contracted backlog of approximately 1,500 missiles and a near-term demand of an additional 1,000 missiles, while the company is producing roughly 20 missiles a month with plans to expand to 35 missiles a month by the end of 2027. As of April 2024 a consortium of Patriot operators consisting of Germany, Romania, Spain, and the Netherlands had placed an order for 1,000 PAC-2 GEM-T missiles, with the bulk of production to take place in Germany in a purpose-built MBDA plant. On November 18, 2024 Boris Pistorius participated in a ground-breaking ceremony at the plant site in Schrobenhausen. "The new facility will cover an area of approximately 6,000 square meters and create more than 300 new jobs. Construction is scheduled for completion in September 2026." General Christian Freuding maintained in July 2025 that the output of the plant would be "under European control".
MIM-104F (PAC-3 CRI)
The PAC-3 upgrade is a significant upgrade to nearly every aspect of the system. It took place in three stages deployed in 1995, 1996 and 2000, and units were designated Configuration 1, 2, or 3. New software update known as PDB 5 (PDB standing for "post deployment build") was released in 1999 with initial support for Configuration-3 ground units and PAC-3 missiles. The system itself saw another upgrade of its WCC, and the communication setup was given a complete overhaul. Due to this upgrade, PAC-3 operators can now see, transmit, and receive tracks on the Link 16 Command and Control (C2) network using a Class 2M Terminal or MIDS LVT Radio. This capability greatly increases the situational awareness of Patriot crews and other participants on the Link 16 network that are able to receive the Patriot local air picture. The software can now conduct a tailored TBM search, optimizing radar resources for search in a particular sector known to have ballistic missile activity, and can support a "keepout altitude" to ensure ballistic missiles with chemical warheads or early release submunitions (ERS) are destroyed at a certain altitude. For Configuration 3 units, the Patriot radar was completely redesigned, adding another traveling wave tube (TWT) that increased the radar's search, detection, tracking, and discrimination abilities. The new radar is designated AN/MPQ-65. It is capable, among other things, of discriminating whether an aircraft is crewed and which of multiple reentering ballistic objects are carrying ordnance.
The PAC-3 upgrade carried with it a new missile design, nominally known as MIM-104F and called PAC-3 by the Army. First deployed in 1997, the PAC-3 missile evolved from the Strategic Defense Initiative's ERINT missile, and so it is dedicated almost entirely to the anti-ballistic missile mission. Due to miniaturization, a single canister can hold four PAC-3 missiles, as opposed to one PAC-2 missile per canister. The PAC-3 missile is more maneuverable than previous variants, due to 180 tiny pulse solid propellant rocket motors mounted in the forebody of the missile, called Attitude Control Motors, or ACMs, which serve to fine align the missile trajectory with its target to achieve hit-to-kill capability.
The most significant upgrade to the PAC-3 missile is the addition of a Ka band active radar seeker. This allows the missile to drop its uplink to the system and acquire its target itself in the terminal phase of its intercept, which improves the reaction time of the missile against a fast-moving ballistic missile target. The PAC-3 missile is accurate enough to select, target, and home in on the warhead portion of an inbound ballistic missile. The active radar gives the warhead a "hit-to-kill" (kinetic kill vehicle) capability that eliminates the need for a traditional proximity-fused warhead. The missile still has a small explosive warhead, called a lethality enhancer, a warhead which launches 24 low-speed tungsten fragments in a radial direction to make the missile cross-section greater and enhance the kill probability. This greatly increases the lethality against ballistic missiles of all types. The PAC-3 upgrade has effectively quintupled the "footprint" that a Patriot unit can defend against ballistic missiles of all types, and has considerably increased the system's lethality and effectiveness against ballistic missiles. It has increased the scope of ballistic missiles that Patriot can engage, which now includes several intermediate ranges. However, despite its increases in ballistic missile defense capabilities, the PAC-3 missile has a shorter range and a smaller explosive warhead compared to older Patriot missiles, making it a less capable interceptor of atmospheric aircraft and air-to-surface missiles. During initial production run, range was increased and other cost-reducing enhancements were incorporated to the PAC-3 missile, with the final variant renamed PAC-3 Cost Reduction Initiative (CRI). Since the PAC-3 ground units can control both M901 PAC-2 launchers and M902/M903 PAC-2/PAC-3 launchers, Patriot batteries employ a mix of PAC-3 hit-to-kill active missiles and PAC-2 GEM-T blast fragmentation warhead semi-active missiles to counter both ballistic missile and aircraft threats. While the PAC-2 is able to intercept targets up to an altitude of 20 km (66,000 ft), the PAC-3 can destroy incoming missiles at an altitude of 40 km (130,000 ft). Lockheed Martin proposed an air-launched variant of the PAC-3 missile for use on the F-15C Eagle, the F-22 Raptor and the P-8A Poseidon. According to Lockheed Martin, PAC-3 CRI can be quad-packed into a VLS cell; though the Navy is considering the single-packed PAC-3 MSE version as its replacement for the SM-2 missile system, PAC-3 CRI is considered a potential follow-on project offering greater magazine depth as a tradeoff for decreased performance compared to PAC-3 MSE.
PAC-3 MSE
Lockheed Martin Missiles and Fire Control is the prime contractor on the PAC-3 Missile Segment Enhancement upgrade (MSE) to the Patriot air defense system which will make the missile more agile and extend its range by up to 50%.
Patriot's PAC-3 MSE interceptor was selected as the primary interceptor for the new MEADS system when its design and development program began in 2004. MEADS is designed with plug-and-fight capabilities to support data exchange with external sensors and launchers through standardized open protocols for integrated air and missile defense (IAMD), so that MEADS elements can interoperate with allied forces on the move, attaching to and detaching from the battle management network as necessary. MEADS was scheduled to enter service alongside Patriot by 2014, with expectations that existing Patriot batteries will be gradually upgraded with MEADS technology in the long run. Because of economic conditions, in 2013 the U.S. chose to upgrade its Patriot systems instead of buying the MEADS system.
The PAC-3 Missile Segment upgrade consists of the PAC-3 MSE missile, a very agile hit-to-kill interceptor, the M903 Launching Station, a fire solution computer, and an Enhanced Launcher Electronics System (ELES). The PAC-3 Missile Segment Enhancement (MSE) interceptor increases altitude and range through a more powerful dual-pulse motor for added thrust, larger fins that collapse inside current launchers, and other structural modifications for more agility. The PAC-3 MSE is capable of intercepting longer-range theater ballistic missiles. The U.S. Army accepted the first PAC-3 MSE interceptors in October 2015, and Initial Operational Capability (IOC) was declared in August 2016. The new M903 Launching System has a modular design capable of holding a total of 4 PAC-3 launching canisters (16 missiles), 12 PAC-3 MSE canisters (in 3 rows of 4), or 4 PAC-2 GEM canisters. It can mix different missiles, such as 6 PAC-3 MSE canisters (in 3 rows of 2) and either two PAC-3 canisters (8 missiles) or two PAC-2 canisters on the same launcher, down to combinations of a single PAC-2 canister, a single PAC-3 canister (4 missiles), 4 PAC-3 MSE canisters (in 2 rows of 2) or 2 PAC-3 MSE canisters in a single row. In December 2023 it was stated that production of Patriot interceptors was 550 a year and would be increased to 650 a year in 2024. In February 2023, Lockheed Martin showcased integration of PAC-3 MSE missile with Mk 41 VLS used by Aegis BMD and Aegis Ashore. Lockheed announced it is spending $100 million to integrate the missile with the Aegis combat system and plans to test whether it can fire the missiles from a vertical launch system tied into Aegis's command-and-control technology and the SPY-1 radar in early 2024. In 2024, it was integrated with Aegis and launched from a Mark 70 Payload Delivery System VLS launcher at White Sands Missile Range. The PAC-3 MSE interceptor is viewed as a potential long-term replacement for the SM-2 interceptor due to its "high agility" and proven capabilities for "counter-hypersonic, ballistic missile, and cruise missile defense in various tight envelopes". According to Chris Mang, of Lockheed Martin's Missiles and Fire Control division, "the missile's capabilities are only enhanced when it's put in a maritime context and paired with the Aegis system, which has a lot more power than the Army's radar systems." The PAC-3 MSE would fill the gap in engagement envelope at low altitudes and shorter ranges against maneuvering threats, where the SM-6 missile (which must first be boosted to high altitudes before diving down on it target) cannot easily engage; According to Mang, the PAC-3 MSE's miniaturized attitude control motors allow it to engage these targets at ranges under a kilometer. Though PAC-3 MSE is the primary contender for this replacement, PAC-3 CRI missiles are also capable of being fired from the same platforms and are considered a follow-on option if the US Navy shows interest; compared to PAC-3 MSE they provide greater magazine depth (due to quad-pack capability in a VLS cell vs. the MSE's single missile per cell) but are less performant.
SkyCeptor (PAAC-4)
In August 2013, Raytheon and Rafael Advanced Defense Systems announced plans for Patriot Advanced Affordable Capability-4 (PAAC-4), which would integrate the Stunner interceptor from the jointly-funded David's Sling program with Patriot PAC-3 radars, launchers, and engagement control stations. The two-stage, multimode seeking Stunner would replace single-stage, radar-guided PAC-3 missiles produced by Lockheed Martin, providing improved operational performance at 20 percent of the $2 million unit cost of PAC-3 missiles. Israeli program officials have said that a previous teaming agreement between Raytheon and Rafael would allow the U.S. company to assume prime contractor status, and produce at least 60 percent of the Stunner missile in the United States. In 2016 Raytheon announced that it had been authorized to bid SkyCeptor, a Stunner derivative, as part of its Polish Patriot bid. In March 2017 it was announced that Poland will acquire 8 Patriot batteries, with the majority of missiles deployed being SkyCeptors and only a small number of Patriot PAC-3 MSE missiles. Ultimately, Poland did not procure SkyCeptor missiles, ordering a new short-range air defence system based on CAMM and CAMM-ER missiles, integrated with Patriot batteries through the IBCS battle command system. Electromecanica Ploiești, Romania, will start local production of SkyCeptor missile interceptors by 2026.
=== Upgrades === PAC-3 system upgrades continue under the International Engineering Services Program (IESP) which includes all countries that rely on the Patriot for integrated air and missile defense - as of 2022, the United States of America, The Netherlands, Germany, Japan, Israel, Saudi Arabia, Kuwait, Taiwan, Greece, Spain, South Korea, United Arab Emirates, Qatar, Romania, Sweden, Poland, Bahrain, and Switzerland. The PDB 6 software update was released in 2004. This update allowed Configuration-3 to discriminate targets of all types, including anti-radiation missile carriers, helicopters, unmanned aerial vehicles, and cruise missiles. The PDB 7 system upgrade was released in 2013. It improves radar search capabilities with a transition to digital signal processing, resulting in much better reliability and 30% longer range comparing to analog circuits. Processing power of the new command and control computer is higher by several orders of magnitude. Operator's monochrome CRT displays with hard-wired buttons were replaced by two 30-inch (760 mm) color touchscreen LCD monitors.
The PAC-3 Missile Segment Enhancement (MSE) upgrade was fielded in 2015. It includes a new fin design and a more powerful rocket engine. In 2017, the AN/MPQ-65 radar was upgraded with active electronically scanned array (AESA) solid-state gallium nitride (GaN) transmitters in place of conventional traveling-wave tubes with a passive array of transmitters. The new radar has been redesignated AN/MPQ-65A. It includes a bolt-on replacement antenna array and two smaller rear panel arrays which provide 360-degree coverage. During 2018–2023, Raytheon Company will further enhance the system under a modernization task order from the U.S. Army, resulting in Configuration-3+. The order includes five annual, indefinite delivery/indefinite quantity task order awards with a total contract ceiling of more than $2.3 billion, funded by Patriot partner states. The initial $235 million award was allocated in January 2018. The PDB 8 upgrade released in 2018 includes redesigned fire control computers which support MSE capabilities, new weapons control computers with increased processing power, and software enhancements to radar search and target detection and identification which help reduce friendly fire incidents. The latest PDB 8.1 software started testing in 2019 and will reach operational status by 2023. It adds a revamped game-style GUI named Warfighter to Machine Interface (WMI) which employs 3D graphics to render the terrain and the airspace.
Future upgrades to the Patriot system will include the new Lower Tier Air and Missile Defense Sensor or LTAMDS with support for a Integrated Air and Missile Defense Battle Command System (IBCS) - which will integrate Patriot's LTAMDS, AN/MPQ-53 and AN/MPQ-65/65A radars with AN/MPQ-64 Sentinel and AN/TPS-80 G/ATOR, GhostEye MR (NASAMS), MFCR and SR from MEADS, AN/SPY-1 and AN/SPY-6 (Aegis BMD), AN/TPY-2 (THAAD and GMD) and AN/APG-81 (F-35 Lightning II) radars - and Mode 5 transponder interrogation in the identification friend or foe system. In February 2025, Raytheon's LTAMDS radar successfully completed a live-fire test, detecting and tracking a high-speed cruise missile and guiding a PAC-2 GEM-T interceptor to neutralize the threat. As part of an ongoing U.S. Army test program, LTAMDS continues advancing toward full deployment, with strong international interest and a $2 billion contract to supply radars to the U.S. and Poland. In May 2025, Lockheed Martin received a $114.6 million contract from the United States Army for Engineering and Manufacturing Development (EMD) work related to the Remote Interceptor Guidance-360 (RIG-360) system for the Patriot PAC-3 missile family. According to Lockheed Martin, the RIG-360 architecture is intended to provide 360-degree in-flight communication and engagement capability through integration with the Integrated Battle Command System (IBCS), addressing limitations associated with the Patriot system's traditional sector-focused radar coverage. The contract also included work on containerized launcher concepts and prototype production, with completion scheduled for 2027.
== Patriot battalion == In the U.S. Army, the Patriot System is designed around the battalion echelon. A Patriot battalion consists of a headquarters battery, which includes the Patriot ICC and its operators, a maintenance company, and between four and six "line batteries", which are the actual launching batteries that employ the Patriot systems. Each line battery consists of (nominally) six launchers and three or four platoons: Fire Control platoon, Launcher platoon, and a Headquarters/Maintenance platoon - either a single platoon or separated into two separate units, at the battery commander's discretion. The Fire Control platoon is responsible for operating and maintaining the "big 4", radar, the engagement control station, the antenna mast group, and the electric power plant. The launcher platoon operates and maintains the launchers. The Headquarters/Maintenance platoon(s) provide the battery with maintenance support and a headquarters section. The Patriot line battery is commanded by a captain and usually consists of between 70 and 90 soldiers. The Patriot battalion is commanded by a lieutenant colonel and can include as many as 600 soldiers. Once deployed, the system requires a crew of only three individuals to operate. The Tactical Control Officer (TCO), usually a lieutenant, is responsible for the operation of the system. The TCO is assisted by the Tactical Control Assistant (TCA). Communications are handled by the third crewmember, the communications system specialist. A "hot-crew" composed of an NCOIC (usually a Sergeant) and one or more additional launcher crew members is on-hand to repair or refuel launching stations. A reload crew is on standby to replace spent canisters after missiles are launched. The ICC crew is similar to the ECS crew at the battery level, except its operators are designated as the Tactical Director (TD) and the Tactical Director Assistant (TDA). Patriot battalions prefer to operate in a centralized fashion, with the ICC controlling the launches of all of its subordinate launching batteries through the secure UHF PADIL communications network.
The dismounted Patriot ICC (D-PICC) is a set of equipment which is composed of the same hardware as that at battalion level, but which distributes command and control over the launching batteries, which allows the batteries to disperse over a wider geographic area, with no loss of command and control. D-PICC is deploying to Pacific Command first. U.S. Army Patriot battalions have been heavily deployed, and for years maintained the highest operational tempo across any units in the service with the longest deployments.
