The Aegis Combat System is an American integrated naval weapons system, which uses computers and radars to track and guide weapons to destroy enemy targets. It was developed by the Missile and Surface Radar Division of RCA, and it is now produced by Lockheed Martin.
Initially used by the United States Navy, Aegis is now used also by the Japan Maritime Self-Defense Force, Spanish Navy, Royal Norwegian Navy, Republic of Korea Navy, and Royal Australian Navy, and is planned for use by the Royal Canadian Navy. As of 2022, a total of 110 Aegis-equipped ships have been deployed, and 71 more are planned (see operators).
Aegis BMD (Ballistic Missile Defense) capabilities are being developed as part of the NATO missile defense system.
Etymology The word "Aegis" is a reference that dates back to Greek mythology, with connotations of a protective shield, as the Aegis was the buckler (shield) of Zeus, worn by Athena.
Overview
The Aegis Combat System (ACS) implements advanced command and control (command and decision, or C&D, in Aegis parlance). It is composed of the Aegis Weapon System (AWS), the fast-reaction component of the Aegis Anti-Aircraft Warfare (AAW) capability, along with the Phalanx Close In Weapon System (CIWS), and the Mark 41 Vertical Launch System.Originally, the first five ships of the United States' Aegis equipped Ticonderoga-class cruisers were outfitted with Mark-26 twin-arm missile launchers; however, the ships with this system have been decommissioned and are no longer in service. Mk 41 VLS is available in different versions that vary in size and weight. There are three lengths: for the self-defense version, for the tactical version, and for the strike version. The empty weight for an 8-cell module is for the self-defense version, for the tactical version, and for the strike version, thus incorporating anti-submarine warfare (ASW) systems and Tomahawk Land Attack Cruise Missiles (TLAM). Shipboard torpedo and naval gunnery systems are also integrated.
AWS, the heart of Aegis, comprises the AN/SPY-1 Radar, MK 99 Fire Control System, Weapon Control System (WCS), the Command and Decision Suite, and Standard Missile family of weapons; these include the basic RIM-66 Standard, the RIM-156 Standard ER extended range missile, and the newer RIM-161 Standard Missile 3 designed to counter ballistic missile threats. A further SM-2 based weapon, the RIM-174 Standard ERAM (Standard Missile 6) was deployed in 2013. Individual ships may not carry all variants. Weapons loads are adjusted to suit assigned mission profile. The Aegis Combat System is controlled by an advanced, automatic detect-and-track, multi-function three-dimensional passive electronically scanned array radar, the AN/SPY-1. Known as "the Shield of the Fleet", the SPY high-powered (6 megawatt) radar is able to perform search, tracking, and missile guidance functions simultaneously with a track capacity of well over 100 targets at more than .. However, the AN/SPY-1 Radar is mounted lower than the AN/SPS-49 radar system and so has a reduced radar horizon.
The Aegis system communicates with the Standard missiles through a radio frequency (RF) uplink using the AN/SPY-1 radar for mid-course update missile guidance during engagements, but still requires the AN/SPG-62 fire-control radar for terminal guidance. This means that with proper scheduling of intercepts, a large number of targets can be engaged simultaneously.
The computer-based command-and-decision (C&D) element is the core of the Aegis Combat System and came from the Naval Tactical Data System (NTDS) threat evaluation and weapons assignment (TEWA) function.First-Hand:Legacy of NTDS - Chapter 9 of the Story of the Naval Tactical Data System Section 4.3 Building Aegis. Engineering and Technology History Wiki This interface makes the ACS capable of simultaneous operation against almost all kinds of threats.
In December 2019, Lockheed Martin released a promotional video heralding the 50th anniversary of the Aegis combat system.
The United States Coast Guard's Polar Sentinel-class icebreakers will feature a combat system derived from Aegis. The vessels have been said to include "space, weight, and electrical power set aside to carry offensive weapons".
Development
Aegis was initially developed by the Missile and Surface Radar Division of RCA, which was later acquired by General Electric. The division responsible for the Aegis systems became Government Electronic Systems. This, and other GE Aerospace businesses, were sold to Martin Marietta in 1992.Lenorovitz, Jeffrey. "GE Aerospace to merge into Martin Marietta" Aviation Week & Space Technology. November 30, 1992. Accessed on July 19, 2007 This became part of Lockheed Martin in 1995.
By the late 1950s, the U.S. Navy replaced guns with guided missiles on its ships. These were sufficient weapons but by the late 1960s, the U.S. Navy recognized that reaction time, firepower, and operational availability in all environments did not match the anti-ship missile threat. The new threat of Soviet anti-ship missiles exposed a weakness in contemporary naval radar. The requirements of both tracking and targeting these missiles was limited by the number of radars on each ship, which was typically 2–4. In 1958 the navy started the Typhon Combat System, a prophetic program culminating in the futuristic but unreliable AN/SPG-59 phased array radar, which was never made viable and was cancelled in 1963 to be replaced by the Advanced Surface Missile System (ASMS).
As a result, the U.S. Navy decided to develop a program to defend ships from anti-ship missile threats. An Advanced Surface Missile System (ASMS) was promulgated and an engineering development program was initiated in 1964 to meet the requirements. ASMS was renamed "Aegis" in December 1969 after the aegis, the shield of the Greek god Zeus. The name was suggested by Captain L. J. Stecher, a former Tartar Weapon System manager, after an internal U.S. Navy contest to name the ASMS program was initiated. Captain Stecher also submitted a possible acronym of Advanced Electronic Guided Interceptor System although this definition was never used.Lockheed Martin. "Aegis Heritage". Presentation. November 20, 2002. The main manufacturer of the Aegis Combat System, Lockheed Martin, makes no mention of the name Aegis being an acronym, nor does the U.S. Navy.
In 1970, then-Captain Wayne Meyer was named Manager Aegis Weapons System. Under his leadership the first systems were successfully deployed on various U.S. Navy vessels.
The first Engineering Development Model (EDM-1) was installed in a test ship, , in 1973. During this time frame, the Navy envisioned installing the Aegis Combat System on both a nuclear-powered "strike cruiser" (or CSGN) and a conventionally-powered destroyer (originally designated DDG 47). The CSGN was to be a new, 17,200 ton cruiser design based on the earlier and cruisers. The Aegis destroyer design would be based on the gas turbine powered . When the CSGN was cancelled, the Navy proposed a modified Virginia-class design (CGN 42) with a new superstructure designed for the Aegis Combat System and with a displacement of 12,100 tons. As compared to the CSGN, this design was not as survivable and had reduced command and control facilities for an embarked flag officer. Ultimately this design was also cancelled during the Carter Administration due to its increased cost compared to the non-nuclear DDG 47. With the cancellation of the CGN 42, the DDG 47 Aegis destroyer was redesignated as CG 47, a guided missile cruiser.
The first cruiser of this class was , which used two twin-armed Mark-26 missile launchers, fore and aft. The commissioning of the sixth ship of the class, opened a new era in surface warfare as the first Aegis ship outfitted with the Martin Marietta Mark-41 Vertical Launching System (VLS), allowing a wider missile selection, more firepower, and survivability. The improved AN/SPY-1B radar went to sea in , ushering in another advance in Aegis capabilities. introduced the AN/UYK-43/44 computers, which provide increased processing capabilities.
During 1980, the was designed using an improved sea-keeping hull form, reduced infrared and radar cross-sections, and upgrades to the Aegis Combat System. The first ship of the class, , was commissioned during 1991. A notional design that incorporated the capabilities of a VLS-capable Ticonderoga with a hull and superstructure designed to Arleigh Burke standards, called "Cruiser Baseline", was studied although not built.
Flight II of the Arleigh Burke class, introduced in 1992, incorporated improvements to the SPY-1 radar, and to the Standard missile, active electronic countermeasures, and communications. Flight IIA, introduced in 2000, added a helicopter hangar with one anti-submarine helicopter and one armed attack helicopter. The Aegis program has also projected reducing the cost of each Flight IIA ship by at least $30 million.
Recent Aegis Combat System ships come with active electronically scanned array radars which use solid-state gallium nitride emitters. These include Canadian Surface Combatant (CSC) and Spanish s, which use the AN/SPY-7 radar from Lockheed-Martin, and s which use AN/SPY-6 radar from Raytheon. AN/SPY-6 radar will also be installed in Flight III and Flight IIA Arleigh Burke-class destroyers, giving them Ballistic Missile Defense capability currently deployed on Flight I and Flight II ships.
On April 21, 2026, Lockheed Martin had received a contract from the U.S. government to develop and integrate the PAC-3 MSE into the Aegis Combat System. This allows the Mk 41 VLS to be able to carry and fire such weapons. During the FY 2027, the Navy plans on procuring 405 PAC-3 MSEs for the Arleigh Burke-class destroyer fleet.
Ballistic missile defense
The Aegis Ballistic Missile Defense System (BMD) program by the U.S. Missile Defense Agency enables the Aegis system to act in a sea-based ballistic missile defense function, to counter short- and medium-range ballistic missiles of the variety typically employed by a number of potential opponent states. The program is part of the United States national missile defense strategy and NATO European missile defense system.
BMD capabilities allow vessels equipped with Mk 41 Vertical Launching System (VLS) to intercept ballistic missiles in post-boost phase and prior to reentry, using the RIM-161 Standard Missile 3 (SM-3) mid-course interceptors and the RIM-156 Standard Missile 2 Extended Range Block IV (SM-2ER Block IV) terminal-phase interceptors. The SM-2ER Block IV can engage the ballistic missiles within the atmosphere (i.e. endoatmospheric intercept) in the terminal phase of a missile's trajectory with a blast fragmentation warhead. The Standard Missile 3 is a development of the SM2-ER Block IV, capable of exo-atmospheric intercept (i.e. above the atmosphere) during the midcourse phase; its kinetic warhead (KW) is designed to destroy a ballistic missile's warhead by colliding with it. RIM-174 Standard ERAM (Standard Missile 6) extended range active missile is a further development of the SM-2ER Block IV, which adds a booster and an active radar homing seeker.Aegis Ballistic Missile Defence (BMD) System, United States of America SM-6 can be used for either air defense or ballistic missile defense, providing extended range and increased firepower; it is not intended to replace the SM-2 series of missiles.Sydney J. Freedberg, Jr., "Non-Standard: Navy SM-6 Kills Cruise Missiles Deep Inland" – Breakingdefense.com, 19 August 2014 The SM-6 Block IB includes a larger 21-inch rocket motor that sits on top of the 21-inch booster.