ICBM

I

Introduction

ICBM (ICBM), land-based, fixed, or mobile (on road or rail) rocket-propelled vehicle capable of delivering nuclear warheads on a ballistic trajectory (flight path of the projectile) through space to targets more than 5,500 km (3,417 mi) away.

An ICBM consists of one or more stages of booster rockets and may include a post-boost vehicle carrying two or more warheads. This vehicle, called a multiple independently targetable re-entry vehicle, or MIRV, can be manoeuvred to dispense each warhead on a trajectory to attack a separate target. The targets are normally great distances apart, giving the missile a “footprint” of perhaps 150 km by 450 km (93 mi by 280 mi). ICBMs are the ultimate weapons of mass destruction, capable of destroying vast areas and entire cities. The cost of a modern ICBM, such as the American MX missile, is about $30 million (in 1996 prices).

II

V-2 to MX

The history of the ICBM begins with the German V-2 rocket, about 5,000 of which were launched during World War II between September 6, 1944 and March 27, 1945 mainly against targets in England and continental Europe at ranges of up to 320 km (199 mi). The United States showed little interest in ICBMs until 1954, building winged cruise missiles instead. The Atlas, the United States' original ICBM, was tested over an intercontinental range in November 1958. The original Soviet ICBM was the SS-6, first tested in August 1957, which became famous throughout the world on October 4, 1957, when one put Sputnik 1 into orbit. China, the third country to develop ICBMs, first made a full-range flight test of one in May 1980.

ICBMs are currently deployed by the United States, the former Soviet Union, and China. The first US Atlas ICBM was deployed in 1959, followed by the Minuteman I ICBM in 1962, the Titan in 1963, the Minuteman II in 1965, the Minuteman III in 1970, and the MX in 1986.

The Titan ICBM carried a huge warhead with an explosive power of 9 megatons (MT) equivalent to that of 9 million tonnes of TNT, or the equivalent of 750 Hiroshima atomic bombs. The Minuteman I and Minuteman II carried warheads of about 1 MT. Minuteman III ICBMs deployed after 1979 carry warheads of 335 Kilotons (KT) (equivalent to 335,000 tonnes of TNT). Each MX warhead has an explosive power of 300 KT. The United States began deploying MIRVs, on Minuteman III ICBMs, in 1980, each missile carrying three MIRVed warheads. Each MX ICBM carries ten MIRVs.

III

Soviet and Chinese ICBMs

The first Soviet SS-6 (Sapwood) ICBM was deployed in 1959. Early Soviet ICBMs carried warheads with extremely large explosive powers. The SS-9, for example, carried a warhead of up to 25 MT. Later Soviet ICBMs carried less-powerful warheads. The warheads on later Soviet ICBMs have explosive powers of about 500 KT.

The Soviet Union began deploying MIRVs in 1979, the vast SS-18 and SS-24 ICBMs each carrying ten. SS-24 and SS-25 ICBMs which carry a single warhead are mobile—the former being transportable on railways and the latter on roads. Other types of US and Soviet ICBMs are in fixed hardened (heavily protected) silos.

China probably deploys about 17 ICBMs consisting of 7 DF-5s (first deployed in 1981) and about 10 DF-4s (first deployed in 1979), each carrying a single warhead with an explosive power of at least 2 MT.

IV

Targeting and Strategy

The accuracy at which ICBMs warheads can be delivered to their targets has improved considerably over time. The delivery accuracy is measured by the Circular Error Probable (CEP), which is the radius of the circle around a target of such size that a weapon aimed at the target has a 50 per cent probability of falling within that circle. The CEP of the Soviet SS-11, for example, was about 1,300 m (1,422 yd), whereas the CEP of the SS-25 is about 200 m (183 yd). So far as American ICBMs are concerned, the CEP of the Titan was about 900 m (984 yd) whereas the CEP of the MX is less than 120 m (131 yd).

A nation possessing nuclear weapons power which deploys very accurate nuclear warheads cannot continue to operate a policy of nuclear deterrence by mutual assured destruction. The targets of nuclear deterrence are the enemy's cities, civilian population, and industry. If one power knows that it faces unacceptable death and destruction as a result of a second power's retaliation after the first power has attacked, the first power is less likely to attack in the first place.

Some strategic analysts believe that nuclear deterrence works only with inaccurate nuclear warheads. From the early 1980s, nuclear warheads with the accuracy of those carried on modern ICBMs have been developed, which are capable of destroying even very hardened military targets, such as enemy ICBM silos. This increased accuracy makes an enemy power believe that the missiles are targeted on its strategic military targets rather than on cities. With accurate weapons an enemy power, therefore, no longer believes that its cities are targeted. Nuclear-war fighting, based on the destruction of hostile military forces in a pre-emptive nuclear first strike, therefore becomes the nuclear policy—a radical change of policy which encourages the other side to deploy anti-ballistic missiles (see Strategic Defense Initiative).