An Intercontinental Ballistic Missile (ICBM) is a long-range (greater than 5,500 km or 3,500 miles) ballistic missile typically designed for nuclear weapons delivery, that is, delivering one or more nuclear warheads. Due to their great range and firepower, in an all-out nuclear war, land-based ICBMs and submarines would carry most of the destructive force, with nuclear-armed bombers having the remainder.
ICBMs are differentiated by having greater range and speed than other ballistic missiles: intermediate-range ballistic missiles (IRBMs), medium-range ballistic missiles (MRBMs), short-range ballistic missiles (SRBMs)—these shorter range ballistic missiles are known collectively as theatre ballistic missiles. Categorizing missiles by range is necessarily subjective and the boundaries are chosen somewhat arbitrarily.
While the warheads of theater ballistic missiles are often conventional, ICBMs are nearly inseparable from their connection with nuclear warheads. 'Nuclear ICBM' is seen as a redundant term. Strategic planning avoids the concept of a conventionally tipped ICBM, mainly because any ICBM launch threatens many countries and they are expected to react under a worst-case assumption that it is a nuclear attack. This threat of ICBMs to deliver such a lethal blow so rapidly to targets across the globe has resulted in the interesting fact that there has never been any end-to-end test of a nuclear-armed ICBM.
The development of the world's first practical design for a ICBM, A9/10, intended for use in bombing New York and other American cities, was undertaken in Nazi Germany by the team of Wernher von Braun under Projekt Amerika. The ICBM A9/A10 rocket initially was intended to be guided by radio, but was changed to be a piloted craft after the failure of Operation Elster. The second stage of the A9/A10 rocket was tested a few times in January and February 1945. The progenitor of the A9/A10 was the German V-2 rocket, also designed by von Braun and widely used at the end of World War II to bomb British and Belgian cities. All of these rockets used liquid propellants. Following the war, von Braun and other leading German scientists were secretly transferred to the United States to work directly for the U.S. Army through Operation Paperclip, developing the IRBMs, ICBMs, and launchers.
In 1953, the USSR initiated, under the direction of the reactive propulsion engineer Sergey Korolyov, a program to develop an ICBM. Korolyov had constructed the R-1, a copy of the V-2 based on some captured materials, but later developed his own distinct design. This rocket, the R-7, was successfully tested in August 1957 becoming the world's first ICBM and, on October 4, 1957, placed the first artificial satellite in space, Sputnik.
In the USA, competition between the U.S. armed services meant that each force developed its own ICBM program. The U.S. initiated ICBM research in 1946 with the MX-774. However, its funding was cancelled and only three partially successful launches in 1948, of an intermediate rocket, were ever conducted. In 1951, the U.S. began a new ICBM program called MX-774 and B-65 (later renamed Atlas). The U.S.' first successful ICBM, the 1.44-megaton Atlas D, was launched on July 29, 1959, almost two years after the Soviet R-7 flight.
Military units with deployed ICBMs would first be fielded in 1959, in both the Soviet Union and the United States. The R-7 and Atlas each required a large launch facility, making them vulnerable to attack, and could not be kept in a ready state. The first US base to host ICBMs was F. E. Warren Air Force Base, in Wyoming; the base hosts an ICBM and Heritage Museum.
These early ICBMs also formed the basis of many space launch systems. Examples include Atlas, Redstone, Titan, R-7, and Proton, which was derived from the earlier ICBMs but never deployed as an ICBM. The Eisenhower administration supported the development of solid-fueled missiles such as the LGM-30 Minuteman, Polaris and Skybolt. Modern ICBMs tend to be smaller than their ancestors, due to increased accuracy and smaller and lighter warheads, and use solid fuels, making them less useful as orbital launch vehicles.
The Western view of the deployment of these systems was governed by the strategic theory of Mutual Assured Destruction. In the 1950s and 1960s, development began on Anti-Ballistic Missile systems by both the U.S. and USSR; these systems were restricted by the 1972 ABM treaty. An alternative view is that the Soviet Union did not adhere to MAD theory and indeed planned to fight a war involving intense use of nuclear weapons; their avoidance of the development of anti-missile missile systems actually stemming from economic weakness.
The 1972 SALT treaty froze the number of ICBM launchers of both the USA and the USSR at existing levels, and allowed new submarine-based SLBM launchers only if an equal number of land-based ICBM launchers were dismantled. Subsequent talks, called SALT II, were held from 1972 to 1979 and actually reduced the number of nuclear warheads held by the USA and USSR. SALT II was never ratified by the United States Senate, but its terms were nevertheless honored by both sides until 1986, when the Reagan administration "withdrew" after accusing the USSR of violating the pact.
As of 2009, all five of the nations with permanent seats on the United Nations Security Council have operational ICBM systems: all have submarine-launched missiles, and Russia, the United States and China also have land-based missiles. In addition, Russia and China have mobile land-based missiles.
It is speculated by some intelligence agencies that North Korea is developing an ICBM; two tests of somewhat different developmental missiles in 1998 and 2006 were not fully successful. On April 5, 2009, North Korea launched a missile. They claimed that it was to launch a satellite, but there is no proof to back up that claim.
The following flight phases can be distinguished:
Modern ICBMs typically carry multiple independently targetable reentry vehicles (MIRVs), each of which carries a separate nuclear warhead, allowing a single missile to hit multiple targets. MIRV was an outgrowth of the rapidly shrinking size and weight of modern warheads and the Strategic Arms Limitation Treaties which imposed limitations on the number of launch vehicles (SALT I and SALT II). It has also proved to be an "easy answer" to proposed deployments of ABM systems—it is far less expensive to add more warheads to an existing missile system than to build an ABM system capable of shooting down the additional warheads; hence, most ABM system proposals have been judged to be impractical. The first operational ABM systems were deployed in the U.S. during 1970s. Safeguard ABM facility was located in North Dakota and was operational from 1975–1976. The USSR deployed its Galosh ABM system around Moscow in the 1970s, which remains in service. Israel deployed a national ABM system based on the Arrow missile in 1998, but it is mainly designed to intercept shorter-ranged theater ballistic missiles, not ICBMs. The U.S. Alaska-based National missile defense system attained initial operational capability in 2004.
ICBMs can be deployed from multiple platforms:
The last three kinds are mobile and therefore hard to find.
During storage, one of the most important features of the missile is its serviceability. One of the key features of the first computer-controlled ICBM, the Minuteman missile, was that it could quickly and easily use its computer to test itself.
In flight, a booster pushes the warhead and then falls away. Most modern boosters are solid-fueled rocket motors, which can be stored easily for long periods of time. Early missiles used liquid-fueled rocket motors. Many liquid-fueled ICBMs could not be kept fuelled all the time as the cryogenic liquid oxygen boiled off and caused ice formation, and therefore fueling the rocket was necessary before launch. This procedure was a source of significant operational delay, and might allow the missiles to be destroyed by enemy counterparts before they could be used. To resolve this problem the British invented the missile silo that protected the missile from a first strike and also hid fuelling operations underground.
Once the booster falls away, the warhead continues on an unpowered ballistic trajectory, much like an artillery shell or cannon ball. The warhead is encased in a cone-shaped reentry vehicle and is difficult to detect in this phase of flight as there is no rocket exhaust or other emissions to mark its position to defenders. The high speeds of the warheads make them difficult to intercept and allow for little warning striking targets anywhere in the world within minutes.
Many authorities say that missiles also release aluminized balloons, electronic noisemakers, and other items intended to confuse interception devices and radars (see penetration aid).
As the nuclear warhead reenters the Earth's atmosphere its high speed causes friction with the air, leading to a dramatic rise in temperature which would destroy it if it were not shielded in some way. As a result, warhead components are contained within an aluminium honeycomb substructure, sheathed in pyrolytic graphite-epoxy resin composite, with a heat-shield layer on top which is constructed out of 3-Dimensional Quartz Phenolic.
Accuracy is crucial, because doubling the accuracy decreases the needed warhead energy by a factor of four. Accuracy is limited by the accuracy of the navigation system and the available geophysical information.
Strategic missile systems are thought to use custom integrated circuits designed to calculate navigational differential equations thousands to millions of times per second in order to reduce navigational errors caused by calculation alone. These circuits are usually a network of binary addition circuits that continually recalculate the missile's position. The inputs to the navigation circuit are set by a general purpose computer according to a navigational input schedule loaded into the missile before launch.
One particular weapon developed by the Soviet Union (FOBS) had a partial orbital trajectory, and unlike most ICBMs its target could not be deduced from its orbital flight path. It was decommissioned in compliance with arms control agreements, which address the maximum range of ICBMs and prohibit orbital or fractional-orbital weapons.
The U.S. Air Force currently operates 450 ICBMs around three air force bases located primarily in the northern Rocky Mountain states and North Dakota. These are of the LGM-30 Minuteman III ICBM variant only. Peacekeeper missiles were phased out in 2005.
All USAF Minuteman II missiles have been destroyed in accordance with START, and their launch silos have been sealed or sold to the public. To comply with the START II most U.S. multiple independently targetable reentry vehicles, or MIRVs, have been eliminated and replaced with single warhead missiles. However, since the abandonment of the START II treaty, the U.S. is said to be considering retaining 800 warheads on 450 missiles.
MIRVed land-based ICBMs are considered destabilizing because they tend to put a premium on striking first. If we assume that each side has 100 missiles, with five warheads each, and further that each side has a 95 percent chance of neutralizing the opponent's missiles in their silos by firing two warheads at each silo, then the side that strikes first can reduce the enemy ICBM force from 100 missiles to about five by firing 40 missiles at the enemy silos and using the remaining 60 for other targets. This first-strike strategy increases the chance of a nuclear war, so the MIRV weapon system was banned under the START II agreement.
The United States Air Force awards two badges for performing duty in a nuclear missile silo or Launch Control Center (LCC). The Missile Badge is presented to enlisted and commissioned maintainers while the Space and Missile Pin is awarded to commissioned Officer operators after completed training and full certification.
Specific types of Soviet ICBMs include:
Specific types of Chinese ICBMs called Dong Feng ("East Wind").
The United Kingdom only deploys United States constructed submarine launched ICBMs. The UK contributes towards the development of the U.S. constructed missiles which it uses.
France only deploys submarine launched ICBMs, with all land based ones decommissioned
North Korea currently does not have any ICBM in its inventory.
India currently does not have any ICBM in its inventory.
Pakistan currently does not have any ICBM in its inventory.