Military Knowledge: AEGIS Defence System; Standard Missiles

Overview of the AEGIS System:

The Aegis Ballistic Missile Defense System (ABMD) is a component of the AEGIS comprehensive combat system. It is an integrated, sea-based defense system designed to protect US naval fleets from enemy aircraft and cruise missiles. The system employs various types of missiles, including the Standard-2 (SM-2), Standard-3 (SM-3), Standard-6 (SM-6), and Sea Sparrow, alongside Phalanx Close-In Weapon System to counter potential threats.

Additionally, Aegis can launch Tomahawk land-attack cruise missiles. A specific subset of Aegis-equipped vessels operates in key regions, including the Mediterranean Sea, Red Sea, Black Sea, Western Pacific, and Persian Gulf, providing a defensive shield against potential ballistic missile attacks from countries such as Russia, China, North Korea, and Iran.

The Aegis anti-ballistic system consists of three main components: sensors, interceptors, and a command and control system.

The main interceptor missile of this system is the RIM-161 Standard Missile 3 (SM-3), which is designed in three versions: Block IA, IB, and IIA. Each version has been improved in range and performance capabilities compared to its predecessor. This missile employs a kinetic warhead to destroy ballistic missile warheads during the midcourse phase of flight, which occurs outside the Earth’s atmosphere. Additionally, the Aegis system utilizes intra-atmospheric missiles such as the SM-2 Block IV and SM-6, designed to intercept missiles in the terminal phase of flight. All of these interceptors are deployed through the Mark 41 Vertical Launch System (VLS).

The primary sensor used in the Aegis system is the AN/SPY-1D radar, which operates in the S-band and provides nearly 360-degree coverage. As technology has advanced, newer Aegis platforms have been equipped with upgraded radars, such as the SPY-6 and SPY-7. Additionally, enhanced Aegis platforms can launch interceptor missiles based on data from long-range sensors, including the THAAD TPY-2 radar, which operates in the X-band.

The anti-ballistic component of the Aegis system is managed by the Aegis comprehensive combat system, which has undergone upgrades over time through hardware and software enhancements known as “Baseline.” The latest version of this system, called Baseline 9, enables a ship to simultaneously conduct air defense and missile defense operations. Previous versions of the software could only support one of these two missions at a time, often requiring Aegis ships to operate in pairs—one ship managing air defense while the other focused on anti-ballistic defense.

Background and history of the development of the Aegis system:

The development of the Aegis system was initially driven by the increasing threat of Soviet anti-ship missiles in the 1960s. The sinking of the Israeli warship Eilat in 1967 by four Soviet-made Styx missiles highlighted the vulnerability of naval assets to new-generation weapons. In the aftermath of World War II, the United States aimed to strengthen its naval fleet, while the Soviet defense strategy relied on utilizing heavy cruise missiles, sometimes equipped with nuclear warheads, launched from smaller vessels or bombers and fighter jets. These missiles, flying at high speeds and close to the water’s surface, made detection and interception extremely difficult.

The United States Navy recognized that existing radar technology was inadequate for tracking and effectively engaging multiple high-speed, near-surface missiles simultaneously. To address this critical gap, the Advanced Missile System (ASMS) program was initiated in 1964, marking the beginning of what would later become known as Aegis. In December 1969, the ASMS program was officially renamed “Aegis,” inspired by the shield of Zeus in Greek mythology.

The Aegis program was later expanded to include the emerging threat of ballistic missiles. In the mid-1980s, the Aegis Anti-Ballistic Missile Defense System (Aegis BMD) program was launched as part of Ronald Reagan’s Strategic Defense Initiative (SDI), informally known as “Star Wars.” This program was developed as a defense measure against potential attacks from long-range ballistic missiles launched by the former Soviet Union.

Initially, the Aegis BMD concept included a space-based railgun system. However, technological limitations prompted the exploration of alternative solutions, leading to the development of anti-ballistic missiles instead. The first successful interception test of the Aegis BMD system occurred in January 2002, marking a significant milestone in its evolution. The experiences gained from the first and second Persian Gulf Wars, alongside the growing proliferation of short- and intermediate-range ballistic missiles by countries like North Korea and Iran in the late 1990s and early 2000s, further emphasized the necessity for a robust sea-based ballistic missile defense capability like Aegis. This evolution transformed Aegis from a purely anti-ship system into one with a crucial anti-ballistic missile capability.

Role of Aegis in the US Navy and the National Missile Defense Program:

As mentioned earlier, the Aegis anti-ballistic system is part of the larger Aegis Combat System. Note that almost all US Navy warships and destroyers are considered Aegis vessels because they’re equipped with the Aegis combat system, which includes sensors, computers, software, displays, and weapon launchers. However, not all these vessels can engage ballistic targets or have received the Aegis BMD upgrade. This article will focus specifically on the Aegis anti-ballistic capabilities.

Ticonderoga-class cruiser

• A total of 27 Ticonderoga-class ships were purchased between 1978 and 1988, and entered service between 1983 and 1994. The Navy retired the first five ships of the class, which were technically built to an older standard, by 2005. Retirement of the remaining 22 ships began in 2022 and has now reached nine, with at least five of the class reportedly upgraded to anti-ballistic capabilities.

Arleigh Burke-class destroyers

• The U.S. Navy began purchasing the DDG-51 class in 1985, with a total of 94 ships expected to be purchased by 2024. The first destroyer of the class entered service in 1991, and a total of 74 ships will be operational by the end of 2023. Retirement of the older ships will begin in fiscal year 2028. The DDG-51 design has been updated many times over the years. The first 28 ships are known as Class I/II, the next 34 as Class IIA, and the next ships as Generation III. The third generation of the class will use the new SPY-6 radar instead of the older SPY-1. According to the Missile Defense Agency, by the end of fiscal year 2025, there will be a total of 56 ships of the class with anti-ballistic capabilities. By 2023, that number had increased to 49, increasing to 69 by fiscal year 2030.

The Aegis missile defense system is a key part of the U.S. and allied strategies to defend against ballistic missiles. It’s part of the U.S. National Ballistic Missile Defense System, mainly designed to protect against short- to intermediate-range ballistic missiles, which have a range of around 2,200 miles (3,500 km). However, recent upgrades have also given it the ability to counter intercontinental ballistic missiles, which can travel up to 6,200 miles (10,000 km). That’s why the system gets its own funding from the Department of Defense’s Missile Defense Agency.

The Aegis system, led by the Missile Defense Agency, is integrated with other components of the Ballistic Missile Defense System (BMDS), such as THAAD and Patriot defense systems, through the Command, Control, Battle Management, and Communications (C2BMC) system. This integration enables a coordinated response to missile threats by utilizing the strengths of each system. As a result, Aegis can support other interceptors by providing long-range surveillance and radar data.

In addition to the United States, the Aegis combat system is currently deployed by Australia, Canada, Japan, South Korea, Norway, and Spain, all of which share intelligence data.

The video above shows a graphical representation of the first live test of an intercontinental ballistic missile (ICBM) interception. On November 17, 2020, a prototype ICBM was launched from the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll in the Marshall Islands, headed toward the Hawaiian Sea. In this test, a destroyer used remote engagement capabilities through the Command and Control Battle Management communications network, as part of a scenario to defend Hawaii. After getting tracking data from the system, the destroyer fired an SM-3 Block IIA missile that successfully hit the target.

Review of the radar and satellite capabilities of the Aegis system:

The Aegis system uses a set of advanced radar systems to detect, track, and engage ballistic missile threats. The main fire control radar for Aegis, the AN/SPY-1, is a Lockheed Martin Advanced Passive Electronically Scanned Array (PESA) radar that operates in the S-band. This powerful radar has four array panels for 360-degree coverage and can search, track, and guide missiles at the same time. Although the official range of the radar is not publicly disclosed, its estimated range is between 310 and 370 kilometers, making it capable of detecting various ballistic, cruise, and air targets.

Originally, Aegis wasn’t built for anti-ballistic missions. Despite policymakers allocating funds to update the system, the SPY-1 radar is still a major weakness in the Aegis chain, limiting interception by standard missiles.

SPY-1 radar gives interceptors enough accuracy to track targets up to about 370 km. This is enough for the Standard-2 missile, which has a range of around 160 km. However, it’s not enough for Standard-3 anti-ballistic missiles, especially the Block IA/B versions with a range of up to 700 km and the Block IIA with a range of up to 2500 km. The SPY-1 radar also has limitations for the Standard-6, which has an active seeker and can reach a range of about 460 km.

Raytheon’s AN/SPY-6 radar, also referred to as AMDR, is the next generation of radar for Aegis. This active electronically scanned array (AESA) radar works in both S and X bands, providing significantly more advanced capabilities.

The system comprises two main radars and a Radar Set Controller (RSC) that coordinates these sensors. The S-band radar is responsible for tasks such as searching for and tracking targets, accurately detecting ballistic missile warheads, and communicating with interceptor missiles. In contrast, the X-band radar is designed for near-horizon search, offering more accurate tracking and guidance for short- and medium-range missiles. This radar is reported to be 30 times more sensitive than the SPY-1, allowing it to handle 30 times more targets. Different versions of this radar, varying in dimensions, are used on various vessels, including the new generation of Arleigh Burke destroyers.

The AN/SPY-7 radar, manufactured by Lockheed Martin, is another advanced radar being integrated into the Aegis system. This radar is currently installed on some Japanese ships equipped with the Aegis system (ASEV), as well as on the Spanish F-110 ships and the Canadian River-class ships. Additionally, the AN/SPY-7 radar is intended for land-based Aegis systems in the United States, specifically in Hawaii and Alaska, as well as in Japan, where it will be deployed in Yamaguchi and Akita. Overall, the AN/SPY-7 radar is expected to be used on more ships belonging to the United States and its allies in the future.

The land-based version of Aegis is being developed under the name Aegis Ashore. This development began in 2014, with the first site opened in Romania in 2016 as part of the NATO missile defense network in Europe. A second site is scheduled to open in Poland in 2024. Additionally, Japan is developing its own land-based version of Aegis in the prefectures of Yamaguchi and Akita. The United States also has three other land-based Aegis systems located in Guam, Hawaii, and Alaska.

Satellite networks serve as the backbone of the Aegis missile defense system, significantly enhancing its range, accuracy, and speed of response. A crucial component of this network is the Space Tracking and Surveillance System (STSS), which is designed to intercept ballistic missiles during all phases of their flight: from launch (boost phase) through the ascent (midcourse phase) and re-entry into the atmosphere. STSS satellites are capable of detecting and tracking a wide variety of missiles, including short-range, intermediate-range, and intercontinental missiles. The data collected by these satellites is transmitted to Aegis-equipped ships, enabling a critical capability known as Launch on Remote, which substantially extends the effective range of interception.

Along with STSS, the Defense Support Program (DSP) and Spaceborne Infrared System (SBIRS) also provide crucial early warning capabilities. By using infrared sensors, these systems pick up the thermal signatures of missile launches early on and transmit valuable data on position and velocity to Aegis and other parts of the US missile defense system.

Review of AEGIS interceptor missiles:

RIM-161 SM-3 missile

The Standard Missile-3 (SM-3) is the main interceptor used in the Aegis system. The SM-3 program was developed as a variant of the Standard SM-2ER Block IV missile, known as NTW-TBMD. Initial testing took place from 1992 to 1995 as part of Project Terrier/LEAP. The first test flight of the RIM-161A SM-3 occurred in September 1999, and the program achieved its first successful intercept of a ballistic target in January 2002. The Standard Missile officially entered operational service in 2005. Its first combat deployment took place in April 2024, when U.S. Navy warships used the missile to intercept ballistic missiles fired by Iran toward Israel.

The SM-3 missile closely resembles the Standard-2 but has two key differences: first, it employs a solid-fuel booster as a third stage, enabling greater range and altitude engagement; second, it uses a kinetic warhead instead of a conventional high-explosive warhead. The SM-3 family is specifically designed to intercept ballistic missiles outside the atmosphere, at altitudes above 100 km. Because ballistic missiles follow a parabolic flight path, they maintain a relatively constant speed after the boost phase and during the midcourse phase or reentry into the atmosphere, losing the ability to perform complex maneuvers. This characteristic allows anti-ballistic interceptors equipped with heat seekers to detect ballistic warheads and destroy them through direct collision.

The different generations of the Standard-3 missile are as follows:

• SM-3 Block IA: Following the prototype, this version was launched to boost reliability, ease of maintenance, and lower costs, marking the first model in this family to go into mass production.
• SM-3 Block IB: Set to enter service in 2010, this missile featured a dual-spectral infrared seeker and a new space propulsion system in its warhead. These upgrades boosted the missile’s ability to counter maneuvering warheads, enabling it to defend against intermediate-range ballistic missiles and some medium-to-long-range missiles.
• SM-3 Block II: For this version, we increased the fuselage diameter to 530 mm and scaled down the wings to boost speed and range. However, this model never made it into operational use.
• SM-3 Block IIA: Co-developed by Raytheon and Mitsubishi Heavy Industries, this system boasted a larger warhead, improved maneuverability, and more advanced sensors. It can also intercept certain intercontinental ballistic missiles (ICBMs) and satellites, and went into service in 2015.

In terms of operational performance, the Block IA and Block IB versions have an estimated range of between 900 and 1,200 kilometers. The more advanced Block IIA version significantly increases this range to around 2,500 kilometers and even exceeds 5,500 kilometers. Regarding engagement altitude, the Block IA and IB versions can intercept targets at altitudes of up to 500 kilometers, while the Block IIA can operate at altitudes between 900 and 1,050 kilometers, depending on the type of target. Additionally, the terminal speed of the Block IA and IB versions is approximately Mach 8.8, whereas the Block IIA can attain a speed equivalent to Mach 13.2.

How the SM-3 interceptor missile works:

When the Aegis missile defense system detects an incoming ballistic missile, an SM-3 interceptor missile is fired from one of the ships in the engagement zone. The Aerojet MK 72 solid-fuel rocket booster launches the SM-3 from the ship’s Mark 41 vertical launch system. Once launched, the missile communicates with the ship that fired it. After the booster burn is complete, the booster separates, and the Aerojet MK 104 solid-fuel rocket motor takes over propulsion while the missile is in the atmosphere. The rocket continues to receive mid-course guidance information from the launch vessel and is also assisted by GPS data.

The ATK MK 136 solid-fuel third-stage rocket motor ignites after the second stage burns out, propelling the missile (if necessary) into the upper atmosphere and providing pulsed propulsion for the SM-3 until the final 30 seconds before interception.

In the final, fourth stage, the third stage engine separates, and the Lightweight Extra-Atmospheric Projectile (LEAP) kinetic warhead begins to search for the target using targeting data from the launch vehicle. Aerojet’s Tunable Direction and Attitude Control System (TDACS) allows the warhead to maneuver in the final phase of engagement. The kinetic warhead’s sensors identify the target and attempt to locate the most vulnerable part of the target, guiding the warhead to that point. If the kinetic warhead successfully engages the target, it generates 130 megajoules of kinetic energy at the point of impact, equivalent to 31 kilograms of TNT, thereby neutralizing the target.

The accompanying video illustrates the four stages, from launch to the moment of interception and destruction of the target.

RIM-161 SM-3 missile specifications:

Type: Kinetic anti ballistic missile
Manufacturer: Raytheon and Aerojet (Block I) and Raytheon and Mitsubishi (Block IIA)
Country of manufacture: USA and Japan
Entered service: 2014 (Block IB)
Length: 6.55 m
Wingspan: 1.57 m
Diameter:
34.3 cm Block I
53.3 cm Block II
Engine: Four-stage solid fuel
Range:
900 km Block IA
1200 km Block IB
5500 + km Block IIA
Ceiling: 1050 km Block IIA
Speed:
8.8 Mach Block IA – IB
13.2 Mach Block IIA
Weight: 1.5 tons
Warhead: Light extra-atmospheric kinetic warhead for Block I and heavy for Block II
Guidance: GPS/INS/SARH/Passive IR homing

RIM-156 SM-2ER missile

The Block IV (RIM-156A) was the first long-range missile in the Standard family, specifically designed for use with Mk 41 vertical launch systems. It features more advanced guidance and control systems than previous models. This version primarily serves as a final-stage interceptor, which means it intercepts and destroys ballistic missiles during the final phase of their flight within the Earth’s atmosphere. The missile has an estimated engagement range of 185 to 370 km and can reach a maximum engagement altitude of up to 33 km, with a top speed of approximately Mach 3.5.

At the time of the Block IV’s development, older missiles like the RIM-67 could only be launched from inclined deck-mounted launchers due to their large size. These launchers were heavy and bulky, restricting their use to larger vessels such as cruisers. In contrast, the SM-2 Block IV’s compatibility with the Mk 41 Vertical Launch System enabled its deployment on Ticonderoga-class cruisers and Arleigh Burke-class destroyers. Development of the Block IV missile began in July 1987, with the first test conducted at White Sands Missile Range in 1990 and its inaugural sea trial occurring in 1994. Initial limited production of the missile was authorized in 1995.

The RIM-156 was not an overall successful interceptor due to instability in the development program. As a result, the U.S. Navy funded modifications for 75 of the 100 RIM-156 missiles that were produced. Of these, five were used for testing, while about 70 modified SM-2 Block IVs remain in the Aegis fleet, providing temporary defense against anti-ship ballistic missiles. The experiences gained from producing the RIM-156 also contributed to the development of the Standard-3 and Standard-6 missile families.

Additionally, it is important to note that the SM-2 missile is the same type that the U.S. military fired twice on July 3, 1988, at Iran Air Flight IR655, resulting in the tragic loss of all 290 passengers on board, including 66 children under the age of 13.

SM-2ER Block IV missile specifications:

Type: Surface-to-air and anti-ship missile
Manufacturer: Raytheon
Country of manufacture: United States
Length: 6.55 m (with booster)
Wingspan: 1.07 m
Diameter: 34.3 cm
Engine: Two-stage solid fuel
Range: 370 km
Ceiling: 24.4 km
Speed: Mach 3.5
Weight: 1.463 tons
Warhead: 64 kg Blast-Frag
Guidance: INS/SARH

RIM-174 SM-6 missile

The ERAM (Standard Extended Range Active Missile), also known as the Standard Missile 6 (SM-6), provides a wide range of multi-mission capabilities, including long-range air defense, terminal ballistic missile defense, and anti-surface attack. The development of the SM-6 addressed a significant gap in long-range air defense following the cancellation of the SM-2ER Block IVA project. Manufactured by Raytheon, the missile utilizes the airframe of the SM-2ER Block IV (RIM-156A) and features an active radar seeker derived from the AIM-120C AMRAAM air-to-air missile.

The SM-6’s development began around 2005, with the first missile being delivered to the United States Navy in April 2011. It achieved initial operational capability in November 2013. In 2016, the SM-6 demonstrated its anti-surface warfare capability, and an air-launched version, the AIM-174B, is anticipated to be introduced in 2024.

The primary purpose of the SM-6 is to counter long-range aerial threats, effectively engaging aircraft, fighters, cruise missiles, and drones at extended ranges. Additionally, the Block IA and IB versions of the missile possess anti-surface warfare capabilities, allowing them to target both surface ships and ground installations. The missile has an official range of 240 miles (approximately 240 km), but in practical scenarios, its range can exceed 250 miles (around 370 km) against ground or sea targets. The air-launched version, the AIM-174B, has an estimated range of 250 miles (approximately 400 km).

The SM-6 can engage targets at altitudes of up to 25 miles (33 km) and at a maximum speed of Mach 3.5. To enable these capabilities, the missile is equipped with a 140-pound (64 kg) high-explosive warhead.

RIM-174 SM-6 missile specifications:

Type: Surface-to-air, anti-ballistic (terminal phase), and anti-ship missile
Manufacturer: Raytheon
Country of manufacture: United States
Entered service: 2013
Length: 6.6 m
Wingspan: 1.57 m
Diameter: 34 cm Block I
53 cm Block II
Engine: Two-stage solid fuel
Range: Up to 500 km
Ceiling: 34 km
Speed: Mach 3.5
Weight: 1.5 tons
Warhead: 64 kg Blast-Frag
Guidance: GPS/INS/ARH, SARH

Overall, the Aegis system serves as the core of the U.S. anti-ballistic defense program, which has two primary objectives. First, it aims to protect the naval fleet and strike groups. Second, it enhances the overall anti-ballistic program by relaying supplementary data to other land-based defense systems. It’s important to note that the Aegis system was initially developed to counter the long-range missiles of North Korea, China, and Russia—countries that have greater access to the oceans and are geographically closer to the United States. Additionally, the technology behind this system has been specifically provided to allied nations neighboring China or Russia.

sources:
RIM-161 Standard Missile 3 , RIM-174 Standard ERAM, RIM-67 Standard, SM-3 Block IIA Missile Excels in First Ever, ICBM Intercept Test, aegis-weapon-system, modernization-program-meets-key-milestones
mda-test-successfully-intercepts-ballistic-missile-target, Aegis, Aegis-Successfully-Engages-Medium-Range-Ballistic-Missile-Target, Aegis, Ten-years-of-aegis-ballistic-missile-defense-operations
us-and-allied-ballistic-missile-defenses-asia-pacific-region, Ten-years-of-aegis-ballistic-missile-defense-operations
leading-way-ballistic-missile-defense, Aegis-continuum-excellence
apl-plays-pivotal-role-successful-ftx-23-missile-defense-test, The-ballistic-missile-threat-to-the-united-states, PDF1 – PDF2 – PDF3 – PDF4 – PDF5 – PDF6 – PDF8 – PDF9 – PDF10 – PDF11 – PDF12 PDF13 – PDF14 – PDF15