Missile

A missile is an airborne ranged weapon propelled through the air by a jet engine or rocket motor. Historically, the word referred to any projectile that could be thrown or launched, and this wider meaning remains in certain contexts. In modern military terminology, however, the term denotes a powered, guided weapon designed to travel towards a predetermined target. Missiles incorporate systems for propulsion, guidance, control, targeting, and payload delivery, and they may be deployed from ground vehicles, ships, submarines, aircraft, or fixed launch sites.

Terminology and Definitions

The word missile derives from the Latin missilis, meaning “that which may be thrown”. It entered English in the early seventeenth century, initially referring to any projectile. As military technology developed, the term evolved to denote propelled and guided weapons.
Modern usage distinguishes between missiles, which possess onboard propulsion and guidance mechanisms, and other airborne weapons. Unguided jet or rocket-propelled devices are generally classified as rocket artillery. Explosive munitions lacking propulsion are described as shells when fired from artillery, or bombs when dropped from aircraft.
Missile systems are typically categorised by launch platform and target type into surface-to-surface, air-to-surface, surface-to-air, and air-to-air classes. They may also be described as strategic or tactical, referring respectively to long-range systems intended for wide-scale impact and shorter-range systems deployed in specific operational theatres.

Historical Development

Propelled projectiles have ancient origins. Early rockets, used principally as propulsion devices for arrows, appeared in China as early as the tenth century. By the medieval and early modern periods, rocket weapons had spread to Korea, the Indian subcontinent, and parts of Europe. The Mysorean rockets used in eighteenth-century India, particularly by the Kingdom of Mysore and the Maratha Confederacy, influenced European designs and led to the development of the Congreve rocket, which saw service during the Napoleonic Wars.
The twentieth century marked a major advance in missile technology. Scientists such as Robert Goddard in the United States and Hermann Oberth in Germany contributed to early experiments in liquid-fuelled and jet-propelled rockets. In the Soviet Union, research laboratories developed solid-fuel rockets during the 1920s.
The first operational missiles appeared during the Second World War. Germany deployed guided weapons including the V-1 flying bomb and the V-2 rocket, which used mechanical autopilot systems to follow pre-set trajectories. Other German programmes produced early anti-ship and surface-to-air missiles using radio command guidance. Although only limited numbers were fielded, these systems established the foundation for post-war missile development.
During the Cold War, advances in nuclear technology created demand for more accurate, longer-range, and faster missiles. Programmes expanded globally, and both superpowers developed intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and a range of tactical systems.

Proliferation and International Controls

The spread of long-range missile technology has raised persistent security concerns, particularly owing to the potential for delivering weapons of mass destruction. Attempts to limit proliferation include the Missile Technology Control Regime (1987) and the International Code of Conduct against Ballistic Missile Proliferation (2002). These voluntary agreements encourage states to share information on planned launches and to restrict the transfer of sensitive technologies.
Recent developments such as hypersonic glide vehicles, dual-use missiles capable of carrying either conventional or nuclear payloads, and anti-satellite missiles are considered emerging challenges for non-proliferation efforts.

Components of Missile Systems

Missiles incorporate several essential subsystems that collectively determine performance and accuracy.
Targeting, Guidance, and Flight ControlMissile guidance enables the weapon to reach its intended target with precision. Guidance systems perform four main functions: tracking the target, calculating the required trajectory, issuing steering commands, and controlling movement through motors or aerodynamic surfaces. Guidance phases typically include launch, mid-course, and terminal sections, which may use different technologies.
Homing guidance employs sensors to detect radiation from or reflected by the target. Key variants include:

• Active radar homing, where the missile carries its own transmitter and receiver.
• Semi-active radar homing, relying on external illumination from a launching aircraft or vessel.
• Passive homing, which detects emissions from the target itself.

Some systems use infrared or laser guidance, while others employ inertial navigation or satellite-based positioning. Command guidance relies on external operators or launch platforms transmitting instructions to the missile during flight.
The flight system manoeuvres the missile based on guidance inputs. This may involve aerodynamic control surfaces such as fins and canards, or thrust vectoring in rocket engines.
PropulsionMissiles may be powered by solid-fuel, liquid-fuel, or hybrid rocket engines. Solid-propellant motors are valued for reliability and rapid deployment. Liquid-propellant engines allow variable thrust and are used in larger systems. Hybrid engines combine solid fuel with liquid oxidiser.
Cruise missiles generally employ jet engines—particularly turbojets—owing to their efficiency and compact design. Ramjets and, in experimental contexts, nuclear-powered engines have also been considered.
Ballistic missiles often employ multiple stages, with sequential ignitions extending range and altitude. Additional launch propulsion may come from devices such as tank guns or catapults.
WarheadsThe warhead contains the destructive payload and may use a range of explosive technologies. High-explosive charges, often shaped for penetration, are common in tactical systems. Strategic missiles may carry nuclear warheads, although chemical, biological, and radiological payloads are technically possible. Secondary destructive effects frequently result from kinetic energy upon impact.

Classification and Operational Roles

Missiles are classified by mission and range:

• Tactical missiles are short-range weapons used for battlefield engagements and localised strikes. They may carry conventional or, less commonly, nuclear payloads.
• Strategic missiles are long-range systems intended for deterrence or large-scale strategic objectives, typically equipped with nuclear warheads.

Launch platforms further divide missiles into surface-to-air, surface-to-surface, air-to-air, and air-to-surface categories, each designed to counter specific threats or support particular operational doctrines.
Missile systems thus represent a complex integration of propulsion, guidance, targeting, and destructive capability, forming a central component of modern military technology and strategic planning.